TWI699410B - Composition for forming functional layer, method for producing composition for forming functional layer, method for producing organic EL element, organic EL device, electronic device - Google Patents

Abstract

The present invention provides a composition for forming a functional layer, a method for producing a composition for forming a functional layer, a method for producing an organic EL device, an organic EL device, and an electronic device that can obtain stable film-forming properties when using a liquid phase process.

The composition for forming a functional layer of the present invention is used when at least one of the functional layers containing an organic material is formed by a liquid phase process, and is characterized in that it contains a solid component for forming a functional layer and has an electron withdrawing base. The first aromatic solvent and the second aromatic solvent with electron donating group, and the boiling point of the second aromatic solvent is higher than the boiling point of the first aromatic solvent.

Description

Composition for forming functional layer, method for producing composition for forming functional layer, method for producing organic EL element, organic EL device, electronic device

The present invention relates to a composition for forming a functional layer, a method for producing a composition for forming a functional layer, a method for producing an organic EL element, an organic EL device, and an electronic device.

As a composition for forming a functional layer, for example, Patent Document 1 discloses that at least one organic layer in an organic EL (Electro-Luminescence) device is formed by a printing method. The composition contains at least one vapor pressure: Coating liquid for organic EL with solvents below 500Pa.

According to the aforementioned Patent Document 1, as the printing method, lithographic printing can be cited, and as the solvent having a vapor pressure of 500 Pa or less, diethylbenzene, trimethylbenzene, triethylbenzene, and nitrobenzene can be cited. It is considered that the organic EL layer can be formed satisfactorily by the printing method based on the configuration of the above-mentioned solvent.

[Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2001-155861

As the printing method, an inkjet method in which liquid (ink) is ejected in the form of droplets from a nozzle of an inkjet head can be cited. If the coating liquid for organic EL of Patent Document 1 is ejected by the inkjet method, alkylbenzenes such as diethylbenzene, trimethylbenzene, and triethylbenzene have a lower boiling point than nitrobenzene. However, there are problems such as easy drying and nozzle clogging, and it is difficult to ensure ejection stability or film flatness.

In addition, nitrobenzene is a polar solvent and has a nitro group as an electron withdrawing group. If a solvent having an electron withdrawing group remains in a functional layer such as an organic EL layer after film formation, the interaction between the functional layer and the electron withdrawing group may affect the device characteristics.

The purpose of the present invention is to solve at least a part of the above-mentioned problems, which can be realized as the following forms or application examples.

[Application example] The composition for forming a functional layer of this application example is used when at least one of the functional layers containing organic materials is formed by a liquid phase process, and is characterized in that it contains a solid component for forming a functional layer , A first aromatic solvent with an electron withdrawing group, and a second aromatic solvent with an electron donating group, and the boiling point of the second aromatic solvent is higher than the boiling point of the first aromatic solvent.

According to this application example, when at least one of the functional layers is formed by a liquid phase process, the first aromatic solvent as a polar solvent ensures the solubility of solid components. In addition, by adding a second aromatic solvent with a higher boiling point than the first aromatic solvent, the drying of the solvent removed from the composition (liquid) for forming a functional layer is slower than when the second aromatic solvent is not included Therefore, it is possible to provide a composition for forming a functional layer that can obtain stable film-forming properties. In addition, during the drying process of the composition (liquid) for forming a functional layer, the interaction (attractive force) between the first aromatic solvent with electron-withdrawing properties and the second aromatic solvent with electron-donating properties follows Evaporation of the group solvent, the first aromatic solvent also evaporates. Therefore, the residue of the first aromatic solvent in the functional layer after film formation can be reduced. That is, it is possible to suppress the influence of the first aromatic solvent having an electron-attracting group on the device characteristics due to remaining in the functional layer.

Regarding the composition for forming a functional layer of the application example, it is preferable that the boiling point of the first aromatic solvent is 200°C or higher, and the boiling point of the second aromatic solvent is 250°C or higher. By the composition of such a solvent, it is possible to provide a composition for forming a functional layer that is suitable for an inkjet method as a liquid phase process and exhibits ejection stability.

Regarding the composition for forming a functional layer of the application example, it is preferable that the electron withdrawing group is a nitro group.

By the composition of this first aromatic solvent, it exhibits high solubility for organic materials.

Regarding the composition for forming a functional layer of the above application example, it is preferable that the electron donating group is an alkoxy group or an amino group.

The composition of this second aromatic solvent exhibits low reactivity to organic materials. Furthermore, an alkoxy group may be bonded to a phenyl group.

Regarding the composition for forming a functional layer of the application example, it is preferable that the content of the second aromatic solvent is 10% or more and 90% or less.

With the composition of this solvent, excellent ejection stability and film flatness can be obtained when the inkjet method is used.

Regarding the composition for forming a functional layer of the above application example, it is more preferable that the content ratio of the second aromatic solvent is equal to or higher than the content ratio of the first aromatic solvent.

With the composition of such a solvent, if the composition for forming a functional layer is applied and dried, the second aromatic solvent can be evaporated and the first aromatic solvent can be surely evaporated and removed. Prevent the first aromatic solvent from remaining in the functional layer.

Regarding the composition for forming a functional layer of the application example, it is characterized in that the first aromatic solvent is selected from nitrobenzene, 2,3-dimethylnitrobenzene, and 2,4-dimethylnitrobenzene At least one of them.

The composition for forming a functional layer of the above application example is characterized in that the second aromatic solvent is selected from the group consisting of trimethoxytoluene, diphenyl ether, 3-phenoxytoluene, benzyl phenyl ether, and amino acid. At least one of benzene and diphenylamine.

With the composition of these solvents, solvents can be obtained relatively easily.

[Application example] The method for producing a composition for forming a functional layer of this application example is a method for producing a composition for forming a functional layer that is used when at least one of the functional layers containing an organic material is formed by a liquid phase process. It is characterized by comprising the steps of dissolving a solid component for forming a functional layer in a first aromatic solvent having an electron withdrawing group, and adding a solid component to the first aromatic solvent in which the solid component for forming a functional layer is dissolved The step of providing a second aromatic solvent for the electron-donating group, and the boiling point of the second aromatic solvent is higher than the boiling point of the first aromatic solvent.

According to this application example, the solid component for forming the functional layer can be more easily dissolved in the first aromatic solvent than in the second aromatic solvent. In addition, if the obtained composition for forming a functional layer is applied and then dried, the drying progresses slowly compared to the case where the second aromatic solvent is not added, and therefore stable film-forming properties are obtained. In addition, due to the interaction (attractive force) between the electron-withdrawing first aromatic solvent and the electron-donating second aromatic solvent, as the second aromatic solvent evaporates, the first aromatic solvent also evaporates, so it can A composition for forming a functional layer in which the first aromatic solvent hardly remains in the formed functional layer is produced.

[Application example] The method for manufacturing an organic EL device of this application example is a method for manufacturing an organic EL device in which a functional layer including a light-emitting layer is sandwiched between a pair of electrodes, and is characterized by including: one of the above-mentioned pair of electrodes The step of applying the composition for forming a functional layer described in the above application example on the electrode; the step of drying and curing the applied composition for forming the functional layer to form at least one of the functional layers.

According to this application example, organic EL devices with excellent device characteristics can be manufactured.

Regarding the manufacturing method of the organic EL device of the application example, it is preferable that the step of coating the functional layer forming composition is to coat the functional layer forming composition on the film forming area on the one electrode by an inkjet method .

With this method, the required amount of composition can be sprayed to the film formation area from the nozzle of the inkjet head without waste, and excellent film flatness can be obtained.

[Application example] The organic EL device of this application example is characterized by including an organic EL element manufactured using the organic EL element manufacturing method described in the above application example.

According to this application example, an organic EL device with excellent photoelectric characteristics can be provided.

[Application example] The electronic device of this application example is characterized by having the organic EL device described in the above application example.

According to this application example, it is possible to provide electronic equipment with excellent photoelectric characteristics.

20‧‧‧Inkjet head

21‧‧‧Nozzle

50‧‧‧Ink for forming hole injection layer as a composition for forming functional layer

60‧‧‧Ink for forming hole transport layer as a composition for forming functional layer

70‧‧‧Ink for forming luminescent layer as a composition for forming functional layer

100‧‧‧Organic EL device

101‧‧‧Component substrate

102‧‧‧Reflective layer

103‧‧‧Insulation film

104‧‧‧Pixel electrode

105‧‧‧Counter electrode

106‧‧‧The next wall

106a‧‧‧As the opening of the film formation area

110R‧‧‧sub pixel

110G‧‧‧sub pixel

110B‧‧‧Sub pixel

130‧‧‧Organic EL element

131‧‧‧hole injection layer

132‧‧‧Hole Transmission Layer

133‧‧‧Light-emitting layer

134‧‧‧Electron transport layer

135‧‧‧Electron injection layer

136‧‧‧Functional layer

1000‧‧‧Personal computer as an electronic machine

1001‧‧‧Main body

1002‧‧‧Keyboard

1003‧‧‧Display unit

1004‧‧‧Display

1100‧‧‧Thin TV (TV)

1101‧‧‧Display

D‧‧‧ink drop

ta‧‧‧Average film thickness in pixel

tc‧‧‧The central film thickness in the pixel

Fig. 1 is a schematic plan view showing the structure of an organic EL device.

Fig. 2 is a schematic cross-sectional view showing the structure of an organic EL element.

3(a) to (d) are schematic cross-sectional views showing a method of manufacturing an organic EL device.

4 is a schematic cross-sectional view showing the film thickness of the central part of the pixel in the functional layer.

Figure 5 (a) ~ (d) are tables showing the evaluation results of the relationship between the solvent composition and the ink ejectability when a polymer hole is used to inject the transport material.

Fig. 6(e)~(g) are tables showing the evaluation results of the relationship between the solvent composition and the ink ejectability when the polymer hole is used to inject the transport material.

Fig. 7(a)~(d) are tables showing the evaluation results of the relationship between solvent composition and ink ejectability when using polymer light-emitting materials.

Fig. 8(e)~(g) are tables showing the evaluation results of the relationship between the solvent composition and ink ejectability when a polymer light-emitting material is used.

Figure 9(a)~(d) are tables showing the evaluation results of the relationship between the solvent composition and the flatness of the film when a polymer hole is used to inject the transport material.

Fig. 10(e)~(g) are tables showing the evaluation results of the relationship between the solvent composition and the flatness of the film when a polymer hole is used to inject the transport material.

Fig. 11(a)~(d) are tables showing the evaluation results of the relationship between solvent composition and film flatness in the case of using polymer light-emitting materials.

Figure 12(e)~(g) shows the solvent composition and the Table of evaluation results of the relationship between film flatness.

Fig. 13(a)~(d) are tables showing the evaluation results of the relationship between solvent composition and film flatness when low-molecular holes are used to inject the transport material.

14(e)~(g) are tables showing the evaluation results of the relationship between solvent composition and film flatness when low-molecular holes are used to inject the transport material.

Fig. 15(a)~(d) are tables showing the evaluation results of the relationship between solvent composition and film flatness when low-molecular luminescent materials are used.

16(e)~(g) are tables showing the evaluation results of the relationship between the solvent composition and the flatness of the film when a low-molecular luminescent material is used.

FIG. 17 is a table showing the evaluation results of the device characteristics of the organic EL devices in Comparative Example 1 to Comparative Example 3 and Example 1 to Example 15.

FIG. 18 is a table showing the evaluation results of the device characteristics of organic EL devices in Comparative Example 4 to Comparative Example 6 and Example 16 to Example 30.

FIG. 19(a) is a schematic diagram showing a notebook personal computer as an example of an electronic device, and (b) is a schematic diagram showing a thin television (TV) as an example of an electronic device.

Hereinafter, an embodiment embodying the present invention will be described based on the drawings. Furthermore, in the drawing used, the explained part is appropriately enlarged or reduced and displayed so that it can be recognized.

(First Embodiment)

<Organic EL Device>

First, an organic EL device including the organic EL element of this embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic plan view showing the structure of an organic EL device, and FIG. 2 is a schematic cross-sectional view showing the structure of an organic EL device.

As shown in FIG. 1, the organic EL device 100 of this embodiment has elements arranged with sub-pixels 110R, 110G, and 110B that obtain red (R), green (G), and blue (B) light emission (luminous colors). Pieces of substrate 101. The sub-pixels 110R, 110G, and 110B are substantially rectangular, and are arranged in a matrix in the display area E of the element substrate 101. Hereinafter, the sub-pixels 110R, 110G, and 110B are sometimes collectively referred to as the sub-pixels 110. The sub-pixels 110 of the same luminous color are arranged in the vertical direction (row direction or the long side direction of the sub-pixel 110) in the pattern, and the sub-pixels 110 of different luminous colors are arranged in the horizontal direction (column direction or the short side of the sub-pixel 110 in the pattern). Direction) arranged in the order of R, G, B. That is, the sub-pixels 110R, 110G, and 110B of different luminous colors are arranged in a so-called stripe pattern. Furthermore, the planar shape and arrangement of the sub-pixels 110R, 110G, and 110B are not limited to this. In addition, the term "substantially rectangular" includes a square, a rectangle, a quadrangular shape with rounded corners, and a quadrangular shape in which two opposing sides are arc-shaped.

The sub-pixel 110R is provided with an organic EL element that emits red (R) light. Similarly, the sub-pixel 110G is provided with an organic EL element that emits green (G) light, and the sub-pixel 110B is provided with an organic EL element that emits blue (B) light.

In the above-mentioned organic EL device 100, three sub-pixels 110R, 110G, and 110B that obtain different luminous colors are used as a display pixel unit, and each sub-pixel 110R, 110G, and 110B is electrically controlled. In this way, full-color display can be realized.

The organic EL element 130 shown in FIG. 2 is provided in each of the sub-pixels 110R, 110G, and 110B. The organic EL element 130 has: a reflective layer 102 provided on the element substrate 101, an insulating film 103, a pixel electrode 104, a counter electrode 105, and a function including a light-emitting layer 133 provided between the pixel electrode 104 and the counter electrode 105 Layer 136.

The pixel electrode 104 functions as an anode, and is respectively provided on the sub-pixels 110R, 110G, and 110B, and is formed using a transparent conductive film such as ITO (Indium Tin Oxide), for example.

The reflective layer 102 disposed under the pixel electrode 104 reflects the light emitted from the functional layer 136 that has passed through the pixel electrode 104 with light permeability to the side of the pixel electrode 104 again. The reflective layer 102 is formed using a metal such as aluminum (Al) or silver (Ag), or an alloy thereof having light reflectivity. Therefore, in order to prevent the occurrence of electricity between the reflective layer 102 and the pixel electrode 104 The insulating film 103 covering the reflective layer 102 is provided. The insulating film 103 is formed using, for example, silicon oxide, silicon nitride, or silicon oxynitride.

The functional layer 136 includes a hole injection layer 131, a hole transport layer 132, a light emitting layer 133, an electron transport layer 134, and an electron injection layer 135 sequentially stacked from the pixel electrode 104 side. In particular, the light-emitting layer 133 selects constituent materials according to the light-emitting color, but here, regardless of the light-emitting color, it is collectively referred to as the light-emitting layer 133. Furthermore, the configuration of the functional layer 136 is not limited to this, and in addition to these layers, an intermediate layer that controls the movement of carriers (holes or electrons) may be provided.

The counter electrode 105 functions as a cathode, and is provided in the form of a common electrode shared by the sub-pixels 110R, 110G, and 110B, and is formed using, for example, Al (aluminum) or an alloy of Ag (silver) and Mg (magnesium).

A hole as a carrier is injected into the light-emitting layer 133 from the side of the pixel electrode 104 as an anode, and electrons as a carrier are injected into the light-emitting layer 133 from the side of the counter electrode 105 as a cathode. In the light-emitting layer 133, excitons (exciton; a state in which holes and electrons are bound to each other due to Coulomb force) are formed by the injected holes and electrons. When the excitons are annihilated (holes and electrons recombine) Time), part of the energy is released as fluorescence or phosphorescence.

In the organic EL device 100, if the counter electrode 105 is configured to have light permeability, since the reflective layer 102 is provided, the light emitted from the light emitting layer 133 can be extracted from the counter electrode 105 side. This type of light emission is called top light emission. In addition, if the reflective layer 102 is removed and the counter electrode 105 is configured to have light reflectivity, it can also be a bottom emission method in which the light emitted from the light emitting layer 133 is extracted from the element substrate 101 side. In this embodiment, the organic EL device 100 is set to a top emission method, which will be described below. Furthermore, the organic EL device 100 of this embodiment is an active driving type light-emitting device having pixel circuits capable of independently driving the respective organic EL elements 130 of the sub-pixels 110R, 110G, and 110B in the element substrate 101. The pixel circuit can adopt a well-known structure, so the diagram of the pixel circuit is omitted in FIG. 2.

In this embodiment, the organic EL device 100 has a partition wall 106 which is connected to the sub-pixel The outer edges of the pixel electrodes 104 in the organic EL elements 130 of 110R, 110G, and 110B overlap each other, and an opening 106a is formed on the pixel electrode 104.

In this embodiment, regarding the functional layer 136 of the organic EL device 130, at least one of the hole injection layer 131, the hole transport layer 132, and the light emitting layer 133 constituting the functional layer 136 is formed by a liquid phase process. The so-called liquid phase process is a method in which a solution (composition for forming a functional layer) containing components and solvents constituting each layer is applied to the opening 106a as a film formation region surrounded by the partition wall 106 and dried, and This forms the layers. In order to form each layer with a desired film thickness, a specific amount of the composition for forming a functional layer must be applied to the opening 106a with high accuracy. In this embodiment, an inkjet method (droplet ejection method) is used as the liquid phase process.

In particular, in the organic EL device 100 of the top emission method, it is preferable that the cross-sectional shape of each layer constituting the functional layer 136 is flat (flat). Regarding the composition for forming a functional layer of this embodiment, in order to make the cross-sectional shape of each layer flat (flat), a specific amount of the composition for forming a functional layer is applied to the entire surface of the opening 106a and dried. In order to ensure the ejection stability during the inkjet method using the composition for forming the functional layer from the nozzle of the inkjet head, and the film flatness of the functional layer 136 in the opening 106a, research on the composition for forming the functional layer The composition of the solvent. The detailed structure of the composition for forming a functional layer will be described below.

<Method of Manufacturing Organic EL Device>

Next, a method of manufacturing an organic EL element as a light-emitting element of this embodiment will be specifically described with reference to FIG. 3. 3(a) to (d) are schematic cross-sectional views showing a method of manufacturing an organic EL device. Furthermore, as described above, the pixel circuit for driving and controlling the organic EL element 130, or the method for forming the reflective layer 102 or the pixel electrode 104 can be a well-known method. Therefore, the steps below are described here for the step of forming the partition wall.

The method of manufacturing the organic EL element 130 of this embodiment has a partition wall forming step (step S1), a surface treatment step (step S2), a functional layer forming step (step S3), and The electrode formation step (step S4).

In the step of forming the partition wall in step S1, as shown in FIG. 3(a), the element substrate 101 on which the reflective layer 102 and the pixel electrode 104 are formed is coated with a thickness of 1 μm to 2 μm, including, for example, a composition for forming a functional layer The photosensitive resin material of the liquid repellent material exhibiting liquid repellency is dried to form a photosensitive resin layer. As a coating method, a transfer method, a slit coating method, etc. are mentioned. As the liquid repellent material, a fluorine compound or a silicone-based compound can be cited. As the photosensitive resin material, a negative polyfunctional acrylic resin can be mentioned. The formed photosensitive resin layer is exposed and developed using an exposure mask corresponding to the shape of the sub-pixel 110 to form a space overlapping the outer edge of the pixel electrode 104 and forming an opening 106a on the pixel electrode 104 Next door 106. Then go to step S2.

In the surface treatment step of step S2, the element substrate 101 on which the partition wall 106 is formed is subjected to surface treatment. The purpose of the surface treatment step is to remove unnecessary materials such as the residue of the partition wall on the surface of the pixel electrode 104, so that the hole injection layer 131, which constitutes the functional layer 136, is formed by the inkjet method (droplet ejection method) in the next step. In the case of the hole transport layer 132 and the light emitting layer 133, the functional layer forming composition containing the functional layer forming material (solid component) is uniformly wetted and spread in the opening 106a surrounded by the partition wall 106. As a surface treatment method, excimer UV (ultraviolet) treatment is performed in this embodiment. Furthermore, the surface treatment method is not limited to the excimer UV treatment, as long as the surface of the pixel electrode 104 can be cleaned, for example, a washing-drying step using a solvent may also be performed. Moreover, if the surface of the pixel electrode 104 is in a clean state, the surface treatment step may not be performed. Furthermore, in this embodiment, a photosensitive resin material containing a liquid repellent material is used to form the partition wall 106, but it is not limited to this, and a photosensitive resin material that does not contain a liquid repellent material may be used to form the partition wall 106. In step S2, plasma processing using a fluorine-based processing gas is performed to impart liquid repellency to the surface of the partition wall 106, and then plasma processing using oxygen as the processing gas is performed to make the surface of the pixel electrode 104 Surface treatment for lyophilization. Then go to step S3.

In the functional layer forming step of step S3, first, as shown in FIG. 3(b), the hole injection layer forming ink 50 as a composition for forming a functional layer containing a hole injection material is applied to the opening 106a. As for the coating method of the ink 50 for forming the hole injection layer, an inkjet method (droplet ejection method) in which the ink 50 for forming the hole injection layer is ejected in the form of droplets D from the nozzle 21 of the inkjet head 20 is adopted. The ejection amount of the droplets D ejected from the inkjet head 20 can be controlled in units of pl (picoliter), and the number of droplets D obtained by dividing a specific amount by the ejection amount of the droplets D is ejected into the opening 106a. The ejected ink 50 for forming a hole injection layer swells in the opening 106a due to the interfacial tension between it and the partition wall 106, but does not overflow. In other words, the concentration of the hole injection material in the hole injection layer forming ink 50 is adjusted in advance so as to be a certain amount that does not overflow from the opening 106a. Then enter the drying step.

In the drying step, for example, vacuum drying (decompression drying step) is adopted, that is, the element substrate 101 coated with the hole injection layer forming ink 50 is placed in a reduced pressure environment, and the solvent is formed from the hole injection layer The ink 50 is evaporated and dried. Thereafter, a baking treatment such as heating at 180° C. for 30 minutes is performed under atmospheric pressure to achieve curing, and the hole injection layer 131 is formed as shown in FIG. 3(c). The hole injection layer 131 is approximately formed with a film thickness of 10 nm-30 nm, but it is not necessarily limited to this according to the selection of the hole injection material described below or the relationship with other layers in the functional layer 136.

Next, the hole transport layer forming ink 60 which is a composition for forming a functional layer containing a hole transport material is used to form the hole transport layer 132. The method of forming the hole transport layer 132 is also performed by the inkjet method (droplet ejection method) in the same manner as the hole injection layer 131. In other words, the ink 60 for forming a hole transport layer is ejected from the nozzle 21 of the inkjet head 20 in the form of a droplet D into the opening 106 a. Furthermore, the ink 60 for forming a hole transport layer applied in the opening 106a is dried under reduced pressure. Thereafter, in an inert gas atmosphere such as nitrogen, a baking treatment of, for example, heating at 180° C. for 30 minutes is performed, thereby forming the hole transport layer 132. The hole transport layer 132 is approximately formed with a film thickness of 10nm to 20nm, but according to the following electrical The selection of the hole transmission material or the relationship with other layers in the functional layer 136 is not necessarily limited to this. In addition, according to the relationship with other layers in the functional layer 136, the hole injection layer 131 and the hole transport layer 132 can also be integrated to form a hole injection transport layer.

Then, the light-emitting layer forming ink 70 which is a composition for forming a functional layer containing a light-emitting layer forming material is used to form the light-emitting layer 133. The method of forming the light-emitting layer 133 is also performed by the inkjet method (droplet ejection method) in the same manner as the hole injection layer 131. That is, the nozzle 21 of the inkjet head 20 ejects a specific amount of the ink 70 for forming a light-emitting layer in the form of a droplet D into the opening 106 a. Furthermore, the light-emitting layer forming ink 70 applied in the opening 106a is dried under reduced pressure. Thereafter, in an inert gas atmosphere such as nitrogen, a baking treatment is performed, for example, by heating at 130° C. for 30 minutes, thereby forming the light-emitting layer 133. The light-emitting layer 133 is formed with a film thickness of approximately 60 nm to 80 nm, but it is not necessarily limited to this according to the selection of the light-emitting layer forming material described below or the relationship with other layers in the functional layer 136.

二唑)(OXD-1)、BCP(Bathocuproine，浴銅靈)、2-(4-聯苯基)-5-(4-第三丁基苯基)-1,2,4-

二唑(PBD)、3-(4-聯苯基)-5-(4-第三丁基苯基)-1,2,4-三唑(TAZ)、4,4'-雙(1,1-雙二苯基乙烯基)聯苯(DPVBi)、2,5-雙(1-萘基)-1,3,4-

二唑(BND)、4,4'-雙(1,1-雙(4-甲基苯基)乙烯基)聯苯(DTVBi)、2,5-雙(4-聯苯基)-1,3,4-

二唑(BBD)等。 Then, the electron transport layer 134 is formed so as to cover the light emitting layer 133. The electron transport material constituting the electron transport layer 134 is not particularly limited. In order to be formed by a gas phase process such as a vacuum evaporation method, for example, BALq, 1,3,5-tri(5-(4-third Butylphenyl)-1,3,4-

Diazole) (OXD-1), BCP (Bathocuproine, bath copper spirit), 2-(4-biphenyl)-5-(4-tertiary butylphenyl)-1,2,4-

Diazole (PBD), 3-(4-Biphenyl)-5-(4-tert-butylphenyl)-1,2,4-triazole (TAZ), 4,4'-bis(1, 1-bis-diphenylvinyl) biphenyl (DPVBi), 2,5-bis(1-naphthyl)-1,3,4-

Diazole (BND), 4,4'-bis(1,1-bis(4-methylphenyl)vinyl)biphenyl (DTVBi), 2,5-bis(4-biphenyl)-1, 3,4-

Diazole (BBD) and so on.

二唑衍生物、

唑衍生物、啡啉衍生物、蒽醌二甲烷衍生物、苯醌衍生物、萘醌衍生物、蒽醌衍生物、四氰基蒽醌二甲烷衍生物、茀衍生物、二苯基二氰基乙烯衍生物、聯苯醌衍生物、羥基喹啉衍生物等。可將該等中之1種或2種以上組合使用。 In addition, three (8-hydroxyquinoline) aluminum (Alq3),

Diazole derivatives,

Azole derivatives, phenanthroline derivatives, anthraquinone dimethane derivatives, benzoquinone derivatives, naphthoquinone derivatives, anthraquinone derivatives, tetracyanoanthraquinone dimethane derivatives, quinone derivatives, diphenyl dicyanide Ethylene derivatives, diphenoquinone derivatives, quinoline derivatives, etc. One or more of these can be used in combination.

The electron transport layer 134 is approximately formed with a film thickness of 20 nm to 40 nm, but according to the above The selection of the sub-transmission material or the relationship with other layers in the functional layer 136 is not necessarily limited to this. Thereby, electrons injected from the counter electrode 105 serving as the cathode can be transported to the light emitting layer 133 well. Furthermore, according to the relationship with other layers in the functional layer 136, the electron transport layer 134 may be omitted.

Then, the electron injection layer 135 is formed so as to cover the electron transport layer 134. The electron injection material constituting the electron injection layer 135 is not particularly limited. In order to be able to be formed by a gas phase process such as a vacuum vapor deposition method, for example, an alkali metal compound or an alkaline earth metal compound can be mentioned.

Examples of alkali metal compounds include alkali metal salts such as LiF, Li ₂ CO ₃ , LiCl, NaF, Na ₂ CO ₃ , NaCl, CsF, Cs ₂ CO ₃ , and CsCl. In addition, examples of alkaline earth metal compounds include alkaline earth metal salts such as CaF ₂ , CaCO ₃ , SrF ₂ , SrCO ₃ , BaF ₂ , and BaCO ₃ . One or two or more of these alkali metal compounds or alkaline earth metal compounds can be used in combination.

The thickness of the electron injection layer 135 is not particularly limited, but is preferably about 0.01 nm or more and 10 nm or less, and more preferably about 0.1 nm or more and 5 nm or less. Thereby, it is possible to efficiently inject electrons into the electron transport layer 134 from the counter electrode 105 serving as the cathode.

Then, in the counter electrode forming step of step S4, the counter electrode 105 as a cathode is formed so as to cover the electron injection layer 135. As the constituent material of the counter electrode 105, it is preferable to use a material with a small work function, and in order to be formed by a gas phase process such as a vacuum evaporation method, for example, Li, Mg, Ca, Sr, La, Ce, Er, Eu, Sc, Y, Yb, Ag, Cu, Al, Cs, Rb, Au or alloys containing them, etc., one or more of these can be combined (for example, multilayer laminates, etc.) use.

Especially when the organic EL device 100 is set to the top emission method as in this embodiment, as the constituent material of the counter electrode 105, it is preferable to use metals such as Mg, Al, Ag, Au, or MgAg, MgAl, MgAu, AlAg And other alloys. By using the above-mentioned metal or alloy, the light transmittance of the counter electrode 105 can be maintained, and the electricity of the counter electrode 105 can be improved. Sub injection efficiency and stability.

The film thickness of the counter electrode 105 in the top emission method is not particularly limited, but is preferably about 1 nm or more and 50 nm or less, and more preferably about 5 nm or more and 20 nm or less.

Furthermore, when the organic EL device 100 is set to the bottom emission method, the counter electrode 105 is not required to have light permeability. Therefore, metals or alloys such as Al, Ag, AlAg, and AlNd are preferably used. By using the aforementioned metal or alloy as the constituent material of the counter electrode 105, it is possible to improve the electron injection efficiency and stability of the counter electrode 105.

The film thickness of the counter electrode 105 in the bottom emission method is not particularly limited, but is preferably about 50 nm or more and 1000 nm or less, and more preferably about 100 nm or more and 500 nm or less.

As shown in FIG. 3(d), if the organic EL element 130 formed by the above-mentioned manufacturing method is impregnated with moisture or oxygen from the outside, the light-emitting function of the functional layer 136 is impaired, and local light-emitting brightness is reduced or not. The dark spot of light. In addition, there is a possibility that the emission lifetime may be shortened. Therefore, in order to protect the organic EL element 130 from moisture, oxygen, etc., it is preferable to coat it with a sealing layer (illustration omitted). As the sealing layer, an inorganic insulating material such as silicon oxynitride (SiON), which has low permeability such as moisture or oxygen, can be used. Furthermore, for example, a sealing substrate such as transparent glass may be attached to the element substrate 101 on which the organic EL element 130 is formed via an adhesive, thereby sealing the organic EL element 130.

In the above-mentioned manufacturing method of the organic EL element 130, the hole injection layer 131, the hole transport layer 132, and the light-emitting layer 133 in the functional layer 136 are formed by a liquid phase process (inkjet method), but only a liquid phase process (inkjet method) Method) It is sufficient to form one of these layers, and the other layers can be formed by a gas phase process such as vacuum evaporation.

Next, regarding the hole injection layer 131, the hole transport layer 132, and the light emitting layer 133, the constituent materials that can be used in the liquid phase process or the gas phase process are described.

[Hole injection transport materials (HIL and HTL materials)]

As a hole injection and transport material suitable for forming the hole injection layer (HIL) 131 or the hole transport layer (HTL) 132, there is no particular limitation, and various p-type polymer materials can be used alone or in combination Or various p-type low-molecular-weight materials.

As the p-type polymer material (organic polymer), for example, poly(2,7-(9,9-di-n-octylpyrene)-(1,4-phenylene-((4-second (Butylphenyl)imino)-1,4-phenylene))(TFB) and other aromatic amine compounds with arylamine skeleton such as polyarylamines, stilbene-bithiophene copolymers, etc. Polypyridine derivatives with a pyrene skeleton or polypyridine derivatives (PF), poly(N-vinylcarbazole) (PVK ), polyvinylpyrene, polyvinylanthracene, polythiophene, polyalkylthiophene, polyhexylthiophene, poly(p-phenylene vinylene) (PPV), poly(thienylene vinylene), pyrene formaldehyde resin, ethyl Carbazole formaldehyde resin or its derivatives, polymethyl phenyl silane (PMPS) and other polysiloxane series, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine])(PTTA ), poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)-benzidine], etc.

The aforementioned p-type polymer material can also be used in the form of a mixture with other compounds. As an example, poly(3,4-ethylenedioxythiophene/styrene sulfonic acid) (PEDOT/PSS) as a mixture containing polythiophene, conductive polymer VERAZOL (trademark) manufactured by Soken Chemical, etc., ELsource (trademark) manufactured by Nissan Chemical as a polyaniline.

唑系化合物，三苯基甲烷、4,4',4"-三(N-3-甲基苯基-N-苯基胺基)三苯基胺(m-MTDATA)、4,4',4"-三(N,N-(2-萘基)苯基胺基)三苯基胺(2-TNATA)、4,4',4"-三(N-咔唑基)三苯基胺(TCTA)之類的三苯基甲烷系化合物，1-苯基-3-(對二甲胺基苯基)吡唑啉之類的吡唑啉系化合物，苯炔(環己二烯)系化合物，三唑之類的三唑系化合物，咪唑之類的咪唑系化合物，1,3,4-

二唑、2,5-二(4-二甲胺基苯基)-1,3,4-

二唑之類的

二唑系化合物，蒽、9-(4-二乙胺基苯乙烯基)蒽之類的蒽系化合物，茀酮、2,4,7-三硝基-9-茀酮、2,7-雙(2-羥基-3-(2-氯苯基胺甲醯基)-1-萘基偶氮)茀酮之類的茀酮系化合物，聚苯胺之類的苯胺系化合物，矽烷系化合物，1,4-二硫酮-3,6-二苯基-吡咯-(3,4-c)吡咯并吡咯之類的吡咯系化合物，Flowlen之類的Flowlen系化合物，卟啉、金屬四苯基卟啉之類的卟啉系化合物，喹吖啶酮之類的喹吖啶酮系化合物，酞菁、酞菁銅(CuPc)、四(第三丁基)酞菁銅、酞菁鐵之類的金屬或無金屬之酞菁系化合物，萘酚菁銅、萘酚菁氧釩、單氯萘酚菁鎵之類的金屬或無金屬之萘酚菁系化合物，N,N'-二(萘-1-基)-N,N'-二苯基-聯苯胺、N,N,N',N'-四苯基聯苯胺之類的聯苯胺系化合物等。再者，PDA-Si為了實現高分子化，於其中添加使用陽離子聚合性化合物：二甲苯雙氧雜環丁烷(東亞合成，Aron Oxetane OXT-121)、自由基聚合起始劑：脂肪族系過氧化雙乙醯基(PEROYL L，日本油脂股 份有限公司)。 Examples of p-type low-molecular materials include: 1,1-bis(4-di-p-tolylaminophenyl) cyclohexane, 1,1'-bis(4-di-p-tolylaminophenyl) Yl)-4-phenyl-cyclohexane (TAPC) and other aryl cycloalkane compounds, 4,4',4"-trimethyltriphenylamine, N,N'-diphenyl-N ,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD), N,N,N',N'-tetraphenyl-1, 1'-biphenyl-4,4'-diamine, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4, 4'-diamine (TPD1), N,N'-diphenyl-N,N'-bis(4-methoxyphenyl)-1,1'-biphenyl-4,4'-diamine (TPD2), N,N,N',N'-Tetra(4-methoxyphenyl)-1,1'-biphenyl-4,4'-diamine (TPD3), N,N'- Bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (α-NPD), triphenylamine-tetramer (TPTE) , 1,3,5-tris-[4-(diphenylamino)benzene](TDAPB), tris-(4-carbazol-9-yl-phenyl)-amine (spiro-) TAD ), tris-p-tolylamine (HTM1), 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (HTM2), N4,N4'-(biphenyl-4, 4'-diyl) bis(N4,N4',N4'-triphenylbiphenyl-4,4'-diamine)(TPT1) and other arylamine compounds, N,N,N', N'-tetraphenyl-p-phenylenediamine, N,N,N',N'-tetra(p-tolyl)-p-phenylenediamine, N,N,N',N'-tetra(m-tolyl) -M-phenylenediamine (PDA), PDA-Si (Mol.Cryst.Liq.Cryst.Vol.462.pp.249-256,2007), N,N'-diphenyl-1,4-phenylenediamine (DPPD) and other phenylenediamine compounds, carbazole, N-isopropylcarbazole, N-phenylcarbazole, VB-TCA (Adv.Mater.2007,19,300-304) Compounds, stilbene compounds such as stilbene, 4-di-p-tolylamino stilbene, OxZ and the like

Azole compounds, triphenylmethane, 4,4',4"-tris(N-3-methylphenyl-N-phenylamino) triphenylamine (m-MTDATA), 4,4', 4"-tris(N,N-(2-naphthyl)phenylamino)triphenylamine (2-TNATA), 4,4',4"-tris(N-carbazolyl)triphenylamine (TCTA) and other triphenylmethane compounds, 1-phenyl-3-(p-dimethylaminophenyl) pyrazoline and other pyrazoline compounds, benzyne (cyclohexadiene) Compounds, triazole compounds such as triazole, imidazole compounds such as imidazole, 1,3,4-

Diazole, 2,5-bis(4-dimethylaminophenyl)-1,3,4-

Diazole and the like

Diazole compounds, anthracene compounds such as anthracene, 9-(4-diethylaminostyryl)anthracene, quinone, 2,4,7-trinitro-9-quinone, 2,7- Bis(2-hydroxy-3-(2-chlorophenylaminomethanyl)-1-naphthylazo) ketone compounds such as quinones, aniline compounds such as polyaniline, silane compounds, 1,4-Dithione-3,6-diphenyl-pyrrole-(3,4-c)pyrrolopyrrole and other pyrrole compounds, Flowlen and other Flowlen compounds, porphyrin, metal tetraphenyl Porphyrin compounds such as porphyrins, quinacridone compounds such as quinacridones, phthalocyanine, copper phthalocyanine (CuPc), copper tetra(tertiary) phthalocyanine, iron phthalocyanine, etc. Metal or metal-free phthalocyanine compounds, copper naphthol cyanine, vanadyl naphthocyanine, monochloronaphthol cyanine gallium or metal-free naphthocyanine compounds, N,N'-bis(naphthalene -1-yl)-N,N'-diphenyl-benzidine, N,N,N',N'-tetraphenylbenzidine and other benzidine-based compounds. Furthermore, in order to realize high molecular weight PDA-Si, a cationic polymerizable compound: xylene dioxetane (Aron Oxetane OXT-121) and a radical polymerization initiator: aliphatic are added to it. Diacetyl peroxide (PEROYL L, Nippon Oil & Fat Co., Ltd.).

Next, regarding the luminescent material (EML material) that obtains fluorescence or phosphorescence, specific examples will be given for each luminescent color and explained.

[Red luminescent material]

First, the red light-emitting material is not particularly limited, and one of various red fluorescent materials and red phosphorescent materials or a combination of two or more can be used.

衍生物、卟啉衍生物、尼祿紅、2-(1,1-二甲基乙基)-6-(2-(2,3,6,7-四氫-1,1,7,7-四甲基-1H,5H-苯并(ij)喹

-9-基)乙烯基)-4H-吡喃-4H-亞基)丙烷二腈(DCJTB)、4-(二氰基亞甲基)-2-甲基-6-(對二甲胺基苯乙烯基)-4H-吡喃(DCM)、聚[2-甲氧基-5-(2-乙基己氧基)-1,4-(1-氰基伸乙烯基伸苯基)]、聚[{9,9-二己基-2,7-雙(1-氰基伸乙烯基)伸茀基}鄰-共聚-{2,5-雙(N,N'-二苯基胺基)-1,4-伸苯基}]、聚[{2-甲氧基-5-(2-乙基己氧基)-1,4-(1-氰基伸乙烯基伸苯基)}-共聚-{2,5-雙(N,N'-二苯基胺基)-1,4-伸苯基}]等。 The red fluorescent material is not particularly limited as long as it emits red fluorescence, and examples include perylene derivatives, europium complexes, benzopyran derivatives, rhodamine derivatives, and benzosulfur.

Derivatives, porphyrin derivatives, Nero Red, 2-(1,1-dimethylethyl)-6-(2-(2,3,6,7-tetrahydro-1,1,7,7 -Tetramethyl-1H,5H-benzo(ij)quine

-9-yl)vinyl)-4H-pyran-4H-ylidene)propane dinitrile (DCJTB), 4-(dicyanomethylene)-2-methyl-6-(p-dimethylamino) Styryl)-4H-pyran (DCM), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-(1-cyanovinylene)], poly [{9,9-Dihexyl-2,7-bis(1-cyanovinylidene) phenylene} o-copolymer-{2,5-bis(N,N'-diphenylamino)-1 ,4-Phenylene}], poly[{2-methoxy-5-(2-ethylhexyloxy)-1,4-(1-cyano vinylene)}-copolymerization-{2 , 5-bis(N,N'-diphenylamino)-1,4-phenylene}] and the like.

The red phosphorescent material is not particularly limited as long as it emits red phosphorescence. Examples include metal complexes such as iridium, ruthenium, platinum, osmium, rhenium, and palladium, and coordination of these metal complexes. At least one of the groups has a phenylpyridine skeleton, a bipyridine skeleton, a porphyrin skeleton, or the like. More specifically, examples include: tris(1-phenylisoquinoline)iridium, bis[2-(2'-benzo[4,5-α]thienyl)pyridine-N,C3'](acetyl Acetone) iridium (Btp2Ir(acac)), 2,3,7,8,12,13,17,18-octaethyl-12H,23H-porphyrin-platinum(II), face-tris(2- Phenyl)-bis(2-(2'-benzo[4,5-α]thienyl)pyridine-N,C3'](acetone) iridium (Bt2Ir(acac)), bis(2-benzene Base pyridine) (acetone) and iridium.

In addition, the red light-emitting layer 133 may also include a host material added with a red light-emitting material as a guest material in addition to the above-mentioned red light-emitting material.

The host material has the function of recombining holes and electrons to generate excitons, and transferring the energy of the excitons (Forster migration or Dexter migration) to the red luminescent material to excite the red luminescent material. In the case of using the above-mentioned host material, for example, the guest material, that is, a red luminescent material, can be used as a dopant incorporated into the host material.

二唑衍生物、矽羅衍生物(SimCP、UGH3)、二咔唑衍生物(CBP、mCP、CDBP、DCB)、寡聚噻吩衍生物、苯并吡喃衍生物、三唑衍生物、苯并

唑衍生物、苯并噻唑衍生物、喹啉衍生物、4,4'-雙(2,2'-二苯基乙烯基)聯苯(DPVBi)、磷衍生物(PO6)等，亦可將該等中之1種或2種以上組合使用。 The host material is not particularly limited as long as it exhibits the above-mentioned function for the red light-emitting material used. When the red light-emitting material contains a red fluorescent material, for example, fused tetrabenzene derivatives, Acene derivatives such as naphthalene derivatives, anthracene derivatives (acene-based materials), stilbene derivatives, perylene derivatives, stilbene benzene derivatives, stilbene amine derivatives, Tris (8-hydroxyquinoline) aluminum complex (Alq3) and other hydroxyquinoline metal complexes (BAql), triphenylamine tetramer and other triarylamine derivatives (TDAPB),

Diazole derivatives, Silox derivatives (SimCP, UGH3), dicarbazole derivatives (CBP, mCP, CDBP, DCB), oligothiophene derivatives, benzopyran derivatives, triazole derivatives, benzo

Azole derivatives, benzothiazole derivatives, quinoline derivatives, 4,4'-bis(2,2'-diphenylvinyl)biphenyl (DPVBi), phosphorus derivatives (PO6), etc. One or two or more of these are used in combination.

In the case of using the red luminescent material (guest material) and host material as described above, the content (doping amount) of the red luminescent material in the red luminescent layer 133 is preferably 0.01~10wt%, more preferably 0.1~ 5wt%. By setting the content of the red luminescent material within the above range, the luminous efficiency can be optimized.

[Green luminescent material]

The green light-emitting material is not particularly limited. For example, various green fluorescent materials and green phosphorescent materials can be cited, and one or two or more of these can be used in combination.

The green fluorescent material is not particularly limited as long as it emits green fluorescence, and examples include coumarin derivatives, quinacridones and their derivatives, 9,10-bis[(9-ethyl- 3-carbazole)-vinylidene]-anthracene, poly(9,9-dihexyl-2,7-vinylidene), poly[(9,9-dioctylethylene-2,7-di Group)-co-(1,4-diphenylene-vinylene-2-methoxy-5-{2-ethyl Hexyloxy}benzene)], poly[(9,9-dioctyl-2,7-divinylidene)-o-copolymer-(2-methoxy-5-(2-ethoxy Hexyloxy)-1,4-phenylene)], poly[(9,9-dioctylpyrene-2,7-diyl)-o-copolymer-(1,4-benzo-{2 ,1',3}-thiadiazole)](F8BT) and so on.

The green phosphorescent material is not particularly limited as long as it emits green phosphorescence. Examples include metal complexes such as iridium, ruthenium, platinum, osmium, rhenium, and palladium. Specifically, they include: (2-Phenylpyridine)iridium (Ir(ppy)3), bis(2-phenylpyridine-N,C2')(acetone) iridium (Ppy2Ir(acac)), face-tris(5- Fluoro-2-(5-trifluoromethyl-2-pyridine)phenyl-C,N]iridium and the like.

In addition, the green light-emitting layer 133 may also include a host material added with a green light-emitting material as a guest material in addition to the above-mentioned green light-emitting material.

As the host material, the same as the host material described in the red light-emitting layer 133 can be used.

[Blue Luminescent Material]

As the blue light-emitting material, for example, various blue fluorescent materials and blue phosphorescent materials can be cited, and one or two or more of these can be used in combination.

唑衍生物、苯并噻唑衍生物、苯并咪唑衍生物、

衍生物、菲衍生物、二苯乙烯基苯衍生物、四苯基丁二烯、4,4'-雙(9-乙基-3-咔唑伸乙烯基)-1,1'-聯苯(BCzVBi)、聚[(9,9-二辛基茀-2,7-二基)-共聚-(2,5-二甲氧基苯-1,4-二基)]、聚[(9,9-二己氧基茀-2,7-二基)-鄰-共聚-(2-甲氧基-5-{2-乙氧基己氧基}伸苯基-1,4-二基)]、聚[(9,9-二辛基茀-2,7-二基)-共聚-(乙炔基苯)]、聚[(9,9-二辛基茀-2,7-二基)-共聚-(N,N'-二苯基)-N,N'-二(對丁基苯基)-1,4-二胺基-苯]]等。 The blue fluorescent material is not particularly limited as long as it emits blue fluorescence. Examples include stilbene amine derivatives such as stilbene diamine compounds, fluoranthene derivatives, and pyrene derivatives. , Perylene and perylene derivatives, anthracene derivatives, benzo

Azole derivatives, benzothiazole derivatives, benzimidazole derivatives,

Derivatives, phenanthrene derivatives, stilbene benzene derivatives, tetraphenylbutadiene, 4,4'-bis(9-ethyl-3-carbazole vinylidene)-1,1'-biphenyl (BCzVBi), poly[(9,9-dioctylpyridine-2,7-diyl)-copolymer-(2,5-dimethoxybenzene-1,4-diyl)], poly[(9 ,9-Dihexyloxy-2,7-diyl)-o-co-(2-methoxy-5-{2-ethoxyhexyloxy}phenylene-1,4-diyl )], poly[(9,9-dioctyl -2,7-diyl)-co-(ethynylbenzene)], poly[(9,9-dioctyl -2,7-diyl )-Copolymerization-(N,N'-diphenyl)-N,N'-bis(p-butylphenyl)-1,4-diamino-benzene]] etc.

The blue phosphorescent material is not particularly limited as long as it emits blue phosphorescence. For example, metal complexes such as iridium, ruthenium, platinum, osmium, rhenium, palladium, etc. can be cited, specifically, bis[4,6-difluorophenylpyridine-N,C2']-picolinic acid Iridium (FIrpic), tris(1-phenyl-3-methylbenzimidazolin-2-ylidene-C,C2')(Ir(pmb)3), bis(2,4-difluorophenylpyridine) )(5-(pyridin-2-yl)-1H-tetrazole)iridium (FIrN4), tris[2-(2,4-difluorophenyl)pyridine-N,C2']iridium, bis[2-( 3,5-Trifluoromethyl)pyridine-N,C2']-pyridinecarboxamide iridium, bis(4,6-difluorophenylpyridine-N,C2')(acetone) iridium, etc.

In addition, the blue light-emitting layer 133 may also include a host material added with a blue light-emitting material as a guest material in addition to the blue light-emitting material described above.

As the host material, the same as the host material described in the red light-emitting layer 133 can be used.

In addition, in this embodiment, the term "low molecular weight" refers to those having a molecular weight of less than 1,000, and the term "high molecular weight" refers to those having a molecular weight of 1,000 or more and having a structure in which a basic skeleton is repeated.

<Composition for forming functional layer>

Next, the composition for forming a functional layer of this embodiment will be described. The composition for forming a functional layer is preferable when forming each of the hole injection layer 131, the hole transport layer 132, and the light-emitting layer 133 in the functional layer 136 of the organic EL device 130 of this embodiment by a liquid phase process (inkjet method) The basic structure is as follows.

The composition for forming a functional layer includes a solid component for forming a functional layer, a first aromatic solvent having an electron withdrawing group, and a second aromatic solvent having an electron donating group, and the second aromatic solvent has a higher boiling point than the first The boiling point of aromatic solvents.

In addition, when the inkjet method is used, it is considered that the composition for forming the functional layer can be stably discharged from the nozzle of the inkjet head (discharge stability), so that the formed functional layer 136 can obtain film flatness. Select and set the content ratio. In addition, the selection of the solvent and the content ratio are set in such a way that the organic EL device 130 including the functional layer 136 formed into the film obtains the desired device characteristics.

<The first aromatic solvent>

The first aromatic solvent having an electron withdrawing group has excellent solubility (good solvent) for the solid component (organic EL material) for forming a functional layer, and considering the ejection stability, the boiling point (bp) is preferably 200°C or higher. Specifically, examples include: nitrobenzene (bp: 210°C) having a nitro group (-NO ₂ group) as an electron withdrawing group, 2,3-dimethylnitrobenzene (bp: 245°C), 2, 4-Dimethylnitrobenzene (bp: 245°C) and the like.

<The second aromatic solvent>

The second aromatic solvent having an electron donating group may not necessarily be a good solvent for the solid component (organic EL material) for forming a functional layer, and preferably has a boiling point (bp) higher than that of the first aromatic solvent and 250°C or higher. Specifically, examples include α,α,4-trimethoxytoluene (bp: 253°C) and diphenyl ether having an alkoxy group (-OR group) or an amino group (-NH ₃ group) as an electron donating group (bp: 258°C), 3-phenoxytoluene (bp: 272°C), benzyl phenyl ether (bp: 288°C), aminobiphenyl (bp: 299°C), diphenylamine (bp: 302°C). Furthermore, R of the alkoxy group is not limited to the alkyl group, and may be a phenyl group. Furthermore, considering the drying properties of the second aromatic solvent, the boiling point (bp) is preferably 350°C or lower.

<Method for producing composition for forming functional layer>

The method for producing the composition for forming a functional layer of this embodiment includes the steps of dissolving the solid component for forming the functional layer in the first aromatic solvent having an electron withdrawing group, and dissolving the solid component for forming the organic layer The step of adding a second aromatic solvent having an electron donating group to the first aromatic solvent. As described above, the first aromatic solvent exhibits higher solubility for the organic EL material as the solid component for forming the functional layer. Therefore, compared with the solid component dissolved in the second aromatic solvent, the solid component Dissolving in the first aromatic solvent will make the blending industry complete in a short time. In addition, by adding a second aromatic solvent with a higher boiling point to the first aromatic solvent, a composition for forming a functional layer that is chemically stable and easy to handle can be produced.

Then, the specific ejection stability and film flatness when using the inkjet method The evaluation methods and evaluation results are explained. In addition, in this embodiment, since the composition for forming a functional layer is applied by an inkjet method, for convenience of description, the composition for forming a functional layer may also be abbreviated as "ink" below.

<Evaluation of ejection stability>

First, the evaluation method and evaluation results of ejection stability will be described with reference to FIGS. 5 to 8. Figures 5(a)~(d) and Figures 6(e)~(g) compare the evaluation results of the relationship between the solvent composition and the ink ejectability when the polymer holes are injected into the transport material. Figures 7(a)~(d) and Figure 8(e)~(g) are tables showing the evaluation results of the relationship between the solvent composition and the ink ejectability when a polymer luminescent material is used.

In the case of the inkjet method, the more the solid component dissolved by the solvent is a polymer material, the easier the solid component will precipitate when the ink in the nozzle dries. Therefore, an example in which the solid component is a polymer material is used to describe the evaluation method of ejection stability. If the ink dries in the nozzle to precipitate solid components, the nozzle will be clogged, and therefore the ejection amount of the droplets ejected from the nozzle will decrease (decrease). Therefore, regarding the evaluation method of ejection stability in this embodiment, when the initial ink ejection amount is set to "1", if the ejection amount of the droplets ejected from the nozzle after being left for 1 hour is between 0.99 and 1.01 If it is within the range, it is recorded as "○ (good)", if it is above 0.95 and less than 0.99, it is recorded as "△ (slightly poor)", if it is less than 0.95, it is recorded as "× (bad)" . As mentioned above, the unit of the ejection amount (volume) of one droplet ejected from the nozzle of the inkjet head is pl (picoliter). In order to obtain the ink ejection amount with high accuracy, in fact, for example, tens of thousands of drops are ejected. The weight is measured for each drop, and the measured weight is divided by the number of ejections (tens of thousands) to calculate the average ink ejection volume per drop.

In Figure 5(a)~(d) and Figure 6(e)~(g), the hole injection transport material (HIL, HTL) as a polymer is selected from the above-mentioned PVK, PF, PPV, PMPS, PTTA, poly [N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)-benzidine], TFB. In addition, the first aromatic solvent A is selected from the above-mentioned nitrobenzene, 2,3-dimethylnitrobenzene, and 2,4-dimethylnitrobenzene. In addition, the first aromatic solvent A and the above-mentioned α,α,4-trimethoxytoluene, diphenyl ether, 3-phenoxytoluene, benzyl phenyl ether, and amine as the second aromatic solvent B are excluded. In addition to the evaluation of the combination of each of biphenyl and diphenylamine, the combination of the above-mentioned first aromatic solvent A and 2-methoxytoluene having a boiling point (bp) of 170°C was also evaluated. 2-Methoxytoluene has an alkoxy group (methoxy group (-OCH ₃ group)) as an electron donating group.

The content ratio (A:B)% of the first aromatic solvent A and the second aromatic solvent B in the mixed solvent is divided into seven types (0:100, 10:90, 30:70, 50:50, 70: 30, 90: 10, 100:0) for evaluation. Furthermore, the content ratio in this embodiment is volume (Vol)%, but the same evaluation result can be obtained in weight (wt)%.

As shown in Figure 5(a), when the solvent is composed of a combination of nitrobenzene and 2-methoxytoluene, regardless of the content ratio in the mixed solvent, the ink ejectability (ejection stability) is evaluated Is "×". When the solvent composition is 2,3-dimethylnitrobenzene or a combination of 2,4-dimethylnitrobenzene and 2-methoxytoluene, the content ratio in the mixed solvent is 0:100, 10 ：At 90, the evaluation of ink ejectability (ejection stability) is "×", and the content ratio (A:B) in the mixed solvent is 30:70, 50:50, 70:30, 90:10, 100:0 When the ink ejectability (ejection stability) is evaluated as "△".

On the other hand, as shown in Figures 5(b)~(d) and Figure 6(e)~(g), the difference between nitrobenzene as the first aromatic solvent A and the second aromatic solvent B When α,α,4-trimethoxytoluene, diphenyl ether, 3-phenoxy toluene, benzyl phenyl ether, aminobiphenyl, and diphenylamine are combined, the content ratio of the mixed solvent (A:B) Except for 100:0, the evaluations of ink ejection properties (ejection stability) are all "○". The ink ejectability (ejection stability) at 100:0 is "×". Use 2,3-dimethylnitrobenzene or 2,4-dimethylnitrobenzene as the first aromatic solvent A, and α,α,4-trimethoxybenzene as the second aromatic solvent B When toluene, diphenyl ether, 3-phenoxytoluene, benzyl phenyl ether, amino biphenyl, and diphenyl amine are combined, the content ratio of the mixed solvent (A:B) is divided by 100:0 Otherwise, the evaluation of ink ejectability (ejection stability) is "○". When the content ratio of the mixed solvent (A:B) is 100:0, the ink ejectability (ejection stability) is "△".

In Fig. 7(a)~(d) and Fig. 8(e)~(g), for the polymer light-emitting material (EML), the above-mentioned poly[{9,9-dihexyl-2 ,7-bis(1-cyanoethylene vinylene) phenylene}-o-copolymer-{2,5-bis(N,N'-diphenylamino)-1,4-phenylene))( In the table, it is recorded as Red-Poly-EM for ease of presentation. As a green light-emitting material, poly[(9,9-dioctylpyri-2,7-diyl)-o-copolymer-(1,4-benzene) And-{2,1',3}-thiadiazole)](F8BT) (in the table for ease of presentation and marked as Green-Poly-EM), as a blue light-emitting material poly[(9,9-dioctyl Base -2,7-diyl)-copolymer-(N,N'-diphenyl)-N,N'-bis(p-butylphenyl)-1,4-diamino-benzene)) ( In the table, it is marked as Blue-Poly-EM for ease of presentation to form ink. The selection method of the first aromatic solvent A and the second aromatic solvent B is the same as in the case of polymer hole injection transport materials (HIL, HTL).

As shown in Figure 7(a), when the solvent is composed of a combination of nitrobenzene and 2-methoxytoluene, regardless of the content ratio in the mixed solvent, the ink ejectability (ejection stability) is evaluated Is "×". When the solvent is composed of 2,3-dimethylnitrobenzene or a combination of 2,4-dimethylnitrobenzene and 2-methoxytoluene, the content ratio (A:B) in the mixed solvent is At 0:100, 10:90, the evaluation of ink ejectability (ejection stability) is "×", and the content ratio (A:B) in the mixed solvent is 30:70, 50:50, 70:30, 90: 10. At 100:0, the ink ejectability (ejection stability) is evaluated as "△".

On the other hand, as shown in Figures 7(b)~(d) and Figure 8(e)~(g), the ratio between nitrobenzene as the first aromatic solvent A and the second aromatic solvent B When α,α,4-trimethoxytoluene, diphenyl ether, 3-phenoxy toluene, benzyl phenyl ether, aminobiphenyl, and diphenylamine are combined, the content ratio of the mixed solvent (A:B) Except for 100:0, the evaluations of ink ejection properties (ejection stability) are all "○". When the content ratio (A:B) of the mixed solvent is 100:0, the ink ejectability (ejection stability) is "×".

Use 2,3-dimethylnitrobenzene or 2,4-dimethylnitrobenzene as the first aromatic solvent A, and α,α,4-trimethoxybenzene as the second aromatic solvent B When toluene, diphenyl ether, 3-phenoxy toluene, benzyl phenyl ether, amino biphenyl, and diphenyl amine are combined, The content ratio of the mixed solvent (A:B) except for 100:0, the evaluation of ink ejectability (ejection stability) is "○". When the content ratio of the mixed solvent (A:B) is 100:0, the ink ejectability (ejection stability) is "△".

As shown in the above evaluation results of ejection stability, when the boiling point (bp) of the solvent (2-methoxytoluene) selected as the second aromatic solvent B is less than 200°C, leave it for 1 hour In this case, the drying of the ink in the nozzle progresses, and the amount of ink ejected becomes unstable (decreased). In addition, even when the first aromatic solvent A is used alone, the ink ejection amount becomes unstable (decreases). On the other hand, when the boiling point (bp) of the solvent selected as the second aromatic solvent B is 250°C or higher, even after 1 hour of standing, the ink in the nozzle is not easily dried and the ink ejection volume is stable .

<Evaluation of Film Flatness>

Next, the evaluation method and evaluation results of film flatness will be described with reference to FIGS. 4 and 9 to 16. Figure 4 is a schematic cross-sectional view showing the film thickness of the central part of the pixel in the functional layer. Figures 9(a)~(d) and 10(e)~(g) show the case of using polymer hole injection transmission materials Table of evaluation results of the relationship between solvent composition and film flatness. Figures 11(a)~(d) and Figure 12(ee)~(g) are tables showing the evaluation results of the relationship between solvent composition and film flatness in the case of using a polymer light-emitting material. Figures 13(a)~(d) and Figure 14(e)~(g) are tables showing the evaluation results of the relationship between solvent composition and film flatness when low-molecular holes are used to inject the transport material. Figures 15(a)~(d) and Figures 16(e)~(g) are tables showing the evaluation results of the relationship between solvent composition and film flatness when low-molecular luminescent materials are used.

In the inkjet method, as described above, a specific amount of ink is ejected into the opening 106a surrounded by the partition wall 106 with high accuracy to ensure the film flatness of the formed functional layer. In addition, it is believed that the solid components contained in the ink are high-molecular materials or low-molecular materials, which will also affect the flatness of the film. Specifically, it is considered that when ink is applied to the opening 106a and dried, the fixing position (film fixing position) at the start of film formation on the side wall of the partition wall 106 differs depending on whether the solid content is a high molecular material or a low molecular material. , This will flatten the dried film Sex has an impact.

As shown in FIG. 4, the film thickness of the formed film at the center of the pixel electrode 104 is set as the central film thickness tc in the pixel, and the average of the film thickness in the range in contact with the pixel electrode 104 is set as the average in the pixel Film thickness ta. These film thicknesses can be measured using a stylus type measuring device, for example. According to the drying process of the ink applied in the opening 106a or the above-mentioned fixed position, the cross-sectional shape of the film after film formation may be raised or recessed in the center of the pixel. That is, the central film thickness tc in the pixel varies.

Regarding the film flatness evaluation method of this embodiment, when the average film thickness ta in the pixel is 0.9 times or more of the center film thickness tc in the pixel and less than 1.2 times the center film thickness tc in the pixel, the film flatness The evaluation is recorded as "○ (good)". At this time, the flatness of the film when fine irregularities are confirmed on the film surface due to the precipitation of solid components is recorded as "● (precipitation)". When the average film thickness ta in the pixel is 1.2 times or more the center film thickness tc in the pixel and less than 1.3 times the center film thickness tc in the pixel, the evaluation of film flatness is recorded as "△ (slightly poor)". When the average film thickness ta in the pixel is 1.3 times or more the center film thickness tc in the pixel, the evaluation of film flatness is recorded as "x (bad)". Furthermore, when the average film thickness ta in the pixel is 1.3 times or more of the center film thickness tc in the pixel and the film surface has obvious irregularities due to the precipitation of solid components, the film flatness evaluation is recorded as "×× (Poor and precipitation)". When there are obvious concavities and convexities on the film surface, if the organic EL element 130 is turned on, the current flowing in the functional layer 136 in the pixel is not uniform, and uneven brightness is observed. Furthermore, the drying and firing conditions of the ink applied in the opening 106a are as shown in the above-mentioned manufacturing method of the organic EL device 130.

In Figure 9(a)~(d) and Figure 10(e)~(g), the hole injection transport material (HIL, HTL) as a polymer is selected from the above-mentioned PVK, PF, PPV, PMPS, PTTA, poly [N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)-benzidine], TFB. In addition, the first aromatic solvent A is selected from the above-mentioned nitrobenzene, 2,3-dimethylnitrobenzene, and 2,4-dimethylnitrobenzene. Also, in addition to the above-mentioned first aromatic solvent A and the above-mentioned α,α,4-trimethoxytoluene, diphenyl ether, 3-phenoxytoluene, benzyl phenyl ether, and amine as the second aromatic solvent B In addition to the evaluation of the combination of each of biphenyl and diphenylamine, the combination of the above-mentioned first aromatic solvent A and 2-methoxytoluene having a boiling point (bp) of 170°C was also evaluated. 2-Methoxytoluene has an alkoxy group (methoxy group (-OCH ₃ group)) as an electron donating group.

In Fig. 11(a)~(d) and Fig. 12(e)~(g), for the polymer light-emitting material (EML), the above-mentioned poly[{9,9-dihexyl-2 ,7-bis(1-cyanoethylene vinylene) phenylene}-o-copolymer-{2,5-bis(N,N'-diphenylamino)-1,4-phenylene))( In the table, it is recorded as Red-Poly-EM for ease of presentation. As a green light-emitting material, poly[(9,9-dioctylpyri-2,7-diyl)-o-copolymer-(1,4-benzene) And-{2,1',3}-thiadiazole)](F8BT) (in the table for ease of presentation and marked as Green-Poly-EM), as a blue light-emitting material poly[(9,9-dioctyl Base -2,7-diyl)-copolymer-(N,N'-diphenyl)-N,N'-bis(p-butylphenyl)-1,4-diamino-benzene)) ( In the table, it is marked as Blue-Poly-EM for ease of presentation to form ink. The selection method of the first aromatic solvent A and the second aromatic solvent B is the same as in the case of polymer hole injection transport materials (HIL, HTL).

The content ratio (A:B)% of the first aromatic solvent A and the second aromatic solvent B in the mixed solvent is divided into seven types (0:100, 10:90, 30:70, 50:50, 70: 30, 90: 10, 100:0) for evaluation. That is, the ink composition is the same as in the case of the evaluation of ejection stability described above.

As shown in Figure 9(a) and Figure 11(a), when the solvent composition is a combination of nitrobenzene and 2-methoxytoluene, and the mixed solvent content ratio (A:B) is 0:100 , The evaluation of film flatness is "××". When the content ratio (A:B) of the mixed solvent is other than 0:100, the evaluation of film flatness is "×". When the solvent composition is 2,3-dimethylnitrobenzene or a combination of 2,4-dimethylnitrobenzene and 2-methoxytoluene, and the content ratio of the mixed solvent (A:B) is 0:100 In this case, the film flatness is evaluated as "××". When the content ratio (A:B) of the mixed solvent is 10:90, 30:70, 50:50, 70:30, 90:10, 100:0, the film flatness is evaluated as "△".

In contrast, as shown in Figure 9(b)~(d) and Figure 10(e)~(g), Figure 11(b)~(d) and Figure 12(e)~(g), it will be Nitrobenzene as the first aromatic solvent A, and α,α,4-trimethoxytoluene, diphenyl ether, 3-phenoxytoluene, benzyl phenyl ether, amino group as the second aromatic solvent B When combining biphenyl and diphenylamine, the content ratio (A:B) of the mixed solvent is 10:90, 30:70, 50:50, 70:30 other than 100:0 and 0:100 , 90:10, the evaluation of film flatness is "○". When the mixed solvent content ratio (A:B) is 0:100, the film flatness is evaluated as "●", and when the mixed solvent content ratio (A:B) is 100:0, the film flatness is evaluated as "× ".

Use 2,3-dimethylnitrobenzene or 2,4-dimethylnitrobenzene as the first aromatic solvent A, and α,α,4-trimethoxybenzene as the second aromatic solvent B When toluene, diphenyl ether, 3-phenoxytoluene, benzyl phenyl ether, aminobiphenyl, and diphenylamine are combined, the content ratio of the mixed solvent (A:B) is 100:0 And 10:90, 30:70, 50:50, 70:30, 90:10 other than 0:100, the evaluation of film flatness is "○". When the mixed solvent content ratio (A:B) is 0:100, the film flatness is evaluated as "●", and when the mixed solvent content ratio (A:B) is 100:0, the film flatness is evaluated as "△" ".

In Figure 13(a)~(d) and Figure 14(e)~(g), the low-molecular hole injection transport material (HIL, HTL) is selected from the above-mentioned VB-TCA, CuPc, TAPC, TPD, α -Among NPD, m-MTDATA, PDA-Si, 2-TNATA, TCTA, TDAPB, spirocyclic TAD, DPPD, DTP, HTM1, HTM2, TPT1, TPTE. In addition, the first aromatic solvent A is selected from the above-mentioned nitrobenzene, 2,3-dimethylnitrobenzene, and 2,4-dimethylnitrobenzene. In addition, the first aromatic solvent A and the above-mentioned α,α,4-trimethoxytoluene, diphenyl ether, 3-phenoxytoluene, benzyl phenyl ether, and amine as the second aromatic solvent B are excluded. In addition to the evaluation of the combination of each of biphenyl and diphenylamine, the combination of the above-mentioned first aromatic solvent A and 2-methoxytoluene having a boiling point (bp) of 170°C was also evaluated. 2-Methoxytoluene has an alkoxy group (methoxy group (-OCH ₃ group)) as an electron donating group.

In Figure 15(a)~(d) and Figure 16(e)~(g), the luminescent material of low molecular weight material (EML), select the host material from the above CBP, BAlq, mCP, CDBP, DCB, PO6, SimCP, UGH3, TDAPB, and select the red luminescent material (guest material) from Bt2Ir(acac), Btp2Ir(acac), and PtOEP The Red dopant. In addition, the Green dopant is selected from Ir(ppy)3 and Ppy2Ir(acac) as the green light-emitting material (guest material). In addition, the Blue dopant selected as the blue light-emitting material (guest material) among FIrpic, Ir(pmb)3, and FIrN4. The selection method of the first aromatic solvent A and the second aromatic solvent B is the same as in the case of the low-molecular hole injection transport material (HIL, HTL).

The content ratio (A:B)% of the first aromatic solvent A and the second aromatic solvent B in the mixed solvent is divided into seven types (0:100, 10:90, 30:70, 50:50, 70: 30, 90: 10, 100:0) for evaluation. That is, the ink composition is the same as in the case of the evaluation of the above-mentioned polymer material.

As shown in Figure 13(a) and Figure 15(a), when the solvent composition is a combination of nitrobenzene and 2-methoxytoluene, and the mixed solvent content ratio (A:B) is 0:100 , The evaluation of film flatness is "××". When the content ratio (A:B) of the mixed solvent is other than 0:100, the evaluation of film flatness is "×". When the solvent composition is 2,3-dimethylnitrobenzene or a combination of 2,4-dimethylnitrobenzene and 2-methoxytoluene, and the content ratio of the mixed solvent (A:B) is 0:100 In this case, the film flatness is evaluated as "××". When the content ratio (A:B) of the mixed solvent is 10:90, 30:70, 50:50, 70:30, 90:10, 100:0, the film flatness is evaluated as "△".

In contrast, as shown in Figure 13(b)~(d) and Figure 14(e)~(g), Figure 15(b)~(d) and Figure 16(e)~(g), it will be used as Nitrobenzene as the first aromatic solvent A, and α,α,4-trimethoxytoluene, diphenyl ether, 3-phenoxytoluene, benzyl phenyl ether, amino group as the second aromatic solvent B When combining biphenyl and diphenylamine, the content ratio (A:B) of the mixed solvent is 10:90, 30:70, 50:50, 70:30 other than 100:0 and 0:100 , 90:10, the evaluation of film flatness is "○". When the content ratio of the mixed solvent (A:B) is 0:100, the film flatness is evaluated as "●", the content ratio of the mixed solvent When (A:B) is 100:0, the evaluation of film flatness is "×".

Use 2,3-dimethylnitrobenzene or 2,4-dimethylnitrobenzene as the first aromatic solvent A, and α,α,4-trimethoxybenzene as the second aromatic solvent B When toluene, diphenyl ether, 3-phenoxytoluene, benzyl phenyl ether, aminobiphenyl, and diphenylamine are combined, the content ratio of the mixed solvent (A:B) is 100:0 And 10:90, 30:70, 50:50, 70:30, 90:10 other than 0:100, the evaluation of film flatness is "○". When the mixed solvent content ratio (A:B) is 0:100, the film flatness is evaluated as "●", and when the mixed solvent content ratio (A:B) is 100:0, the film flatness is evaluated as "△" ". That is, even if the solid component in the ink is a low-molecular material, the same film flatness evaluation as in the case of a polymer material is obtained.

As shown in the evaluation result of film flatness above, when the boiling point (bp) of the solvent (2-methoxytoluene) selected as the second aromatic solvent B is less than 200°C, in the ink drying step , The second aromatic solvent B evaporates before the first aromatic solvent A, the drying speed of the ink becomes faster, and the leveling during film formation cannot be fully performed, so the flatness of the film decreases. On the other hand, when the boiling point (bp) of the solvent selected as the second aromatic solvent B is 250°C or higher, in the ink drying step, the first aromatic solvent A still remains after the first aromatic solvent A has evaporated. 2 Aromatic solvent B, so the drying speed of the ink slows down, and the leveling during film formation is fully carried out, thereby improving the flatness of the film. Among them, when the ink does not contain the first aromatic solvent A that exhibits high solubility for solid components (when the content ratio of the mixed solvent (A:B) is 0:100), the ink is During the drying process of the second aromatic solvent B, which has poor solubility, solid components are easy to precipitate. Also, when the ink does not contain the second aromatic solvent B with a higher boiling point (when the content ratio of the mixed solvent (A:B) is 100:0), during the drying process of the first aromatic solvent A , The drying speed is relatively fast, so the leveling during film formation cannot be carried out sufficiently, and the film flatness decreases.

Based on the evaluation of the ejection stability and the film flatness, the first aromatic solvent A preferably has a boiling point of 200°C or higher, and the second aromatic solvent B preferably has a boiling point of 250. Above ℃. In addition, the content ratio (A:B) of the first aromatic solvent A and the second aromatic solvent B in the mixed solvent is preferably 10:90 to 90:10.

Next, the relationship between the composition (ink) for forming a functional layer and the device characteristics of the organic EL device 130 will be described with reference to comparative examples and examples.

In this embodiment, the device characteristics of the organic EL device 130 include drive voltage, current efficiency, and life half-life time. The driving voltage is the DC voltage value when the light-emitting brightness of the organic EL element 130 becomes a specific value. The smaller the driving voltage, the better. The current efficiency is the value (cd (candle)/A (ampere)) obtained by dividing the luminescence brightness by the current flowing when the luminescence brightness of the organic EL element 130 is set to a specific value. The larger the current efficiency, the better. The life half-life time is the energizing time (h) from the specific value of the light-emitting brightness of the organic EL element 130 until it becomes half-life. The longer the life half-life time, the better. The specific value of the above-mentioned emission brightness is set to, for example, 1000 cd (candle light)/m ² (square meter).

[Comparative Example 1]

Regarding the organic EL device of Comparative Example 1, an ink containing no second aromatic solvent B was used, and the hole injection layer 131, the hole transport layer 132, and the light emitting layer 133 in the functional layer 136 were formed by an inkjet method. Specifically, using nitrobenzene (bp: 210°C) as the first aromatic solvent A, dissolving VB-TCA as a hole injection material in nitrobenzene to obtain an ink, and using the obtained ink to form a film thickness It is a hole injection layer 131 of 10 nm to 30 nm. In addition, an ink obtained by dissolving TFB as a hole transport material in nitrobenzene is used to form a hole transport layer 132 with a film thickness of 10 nm to 20 nm. Furthermore, using an ink obtained by dissolving F8BT (Green-Poly-EM) as a luminescent material for obtaining fluorescence in nitrobenzene, a luminescent layer 133 having a film thickness of 60 nm to 80 nm is formed. The structure of the other electron transport layer 134 and the electron injection layer 135 in the functional layer 136 is as described in the manufacturing method of the organic EL device 130.

[Comparative Example 2]

Regarding the organic EL device of Comparative Example 2, nitrobenzene (bp: 210°C) used as the first aromatic solvent A in which solid components are dissolved is added as the second aromatic solvent B of 2- An ink containing a mixed solvent obtained by methoxy toluene (bp: 170° C.) forms a hole injection layer 131, a hole transport layer 132, and a light emitting layer 133. The layer constituent material or film thickness of each layer is the same as in Comparative Example 1. The content ratio (A:B) of the above-mentioned mixed solvent is 50:50.

[Comparative Example 3]

Regarding the organic EL element of Comparative Example 3, nitrobenzene (bp: 210°C) used as the first aromatic solvent A in which solid components are dissolved is added with 1,3,5- as the second aromatic solvent B. An ink containing a mixed solvent obtained from triethylbenzene (bp: 215° C.) forms a hole injection layer 131, a hole transport layer 132, and a light emitting layer 133. The layer constituent material or film thickness of each layer is the same as in Comparative Example 1. The content ratio (A:B) of the above-mentioned mixed solvent is 60:40.

[Example 1]

Regarding the organic EL device of Example 1, it is used to add 3-phenoxytoluene as the second aromatic solvent B to nitrobenzene (bp: 210°C) as the first aromatic solvent A in which solid components are dissolved. (bp: 272° C.) The obtained ink containing the mixed solvent forms the hole injection layer 131, the hole transport layer 132, and the light emitting layer 133. The layer constituent material or film thickness of each layer is the same as in Comparative Example 1. The content ratio (A:B) of the above-mentioned mixed solvent is 10:90.

[Example 2]

Regarding the organic EL element of Example 2, 3-phenoxytoluene as the second aromatic solvent B is added to nitrobenzene (bp: 210°C) as the first aromatic solvent A in which solid components are dissolved. (bp: 272° C.) The obtained ink containing the mixed solvent forms the hole injection layer 131, the hole transport layer 132, and the light emitting layer 133. The layer constituent material or film thickness of each layer is the same as in Comparative Example 1. The content ratio (A:B) of the above-mentioned mixed solvent is 30:70.

[Example 3]

Regarding the organic EL device of Example 3, 3-phenoxytoluene as the second aromatic solvent B is added to nitrobenzene (bp: 210°C) as the first aromatic solvent A in which solid components are dissolved. (bp: 272° C.) The obtained ink containing the mixed solvent forms the hole injection layer 131, the hole transport layer 132, and the light emitting layer 133. Layer composition material or film thickness of each layer Same as Comparative Example 1. The content ratio (A:B) of the above-mentioned mixed solvent is 50:50.

[Example 4]

Regarding the organic EL element of Example 4, 3-phenoxytoluene as the second aromatic solvent B is added to nitrobenzene (bp: 210°C) as the first aromatic solvent A in which solid components are dissolved. (bp: 272° C.) The obtained ink containing the mixed solvent forms the hole injection layer 131, the hole transport layer 132, and the light emitting layer 133. The layer constituent material or film thickness of each layer is the same as in Comparative Example 1. The content ratio (A:B) of the above-mentioned mixed solvent is 70:30.

[Example 5]

Regarding the organic EL element of Example 5, 3-phenoxytoluene as the second aromatic solvent B is added to nitrobenzene (bp: 210°C) as the first aromatic solvent A in which solid components are dissolved. (bp: 272° C.) The obtained ink containing the mixed solvent forms the hole injection layer 131, the hole transport layer 132, and the light emitting layer 133. The layer constituent material or film thickness of each layer is the same as in Comparative Example 1. The content ratio (A:B) of the above-mentioned mixed solvent is 90:10.

The above-mentioned Examples 1 to 5 are made of nitrobenzene (bp: 210°C) as the first aromatic solvent A and 3-phenoxytoluene (bp: 272°C) as the second aromatic solvent B The content ratio (A:B) of the mixed solvent is different.

[Example 6]

Regarding the organic EL device of Example 6, 2,3-dimethylnitrobenzene (bp: 245°C) used as the first aromatic solvent A in which solid components are dissolved is added as the second aromatic solvent B An ink containing a mixed solvent obtained from 3-phenoxytoluene (bp: 272°C) to form a hole injection layer 131, a hole transport layer 132, and a light emitting layer 133. The layer constituent material or film thickness of each layer is the same as in Comparative Example 1. The content ratio (A:B) of the above-mentioned mixed solvent is 10:90.

[Example 7]

Regarding the organic EL element of Example 7, it was used as the second aromatic compound in 2,3-dimethylnitrobenzene (bp: 245°C) as the first aromatic solvent A in which solid components were dissolved. An ink containing a mixed solvent obtained from 3-phenoxytoluene (bp: 272° C.) of solvent B forms a hole injection layer 131, a hole transport layer 132, and a light emitting layer 133. The layer constituent material or film thickness of each layer is the same as in Comparative Example 1. The content ratio (A:B) of the above-mentioned mixed solvent is 30:70.

[Example 8]

Regarding the organic EL device of Example 8, 2,3-dimethylnitrobenzene (bp: 245°C) used as the first aromatic solvent A in which solid components are dissolved is added as the second aromatic solvent B An ink containing a mixed solvent obtained from 3-phenoxytoluene (bp: 272°C) to form a hole injection layer 131, a hole transport layer 132, and a light emitting layer 133. The layer constituent material or film thickness of each layer is the same as in Comparative Example 1. The content ratio (A:B) of the above-mentioned mixed solvent is 50:50.

[Example 9]

Regarding the organic EL device of Example 9, 2,3-dimethylnitrobenzene (bp: 245°C) used as the first aromatic solvent A in which solid components are dissolved is added as the second aromatic solvent B An ink containing a mixed solvent obtained from 3-phenoxytoluene (bp: 272°C) to form a hole injection layer 131, a hole transport layer 132, and a light emitting layer 133. The layer constituent material or film thickness of each layer is the same as in Comparative Example 1. The content ratio (A:B) of the above-mentioned mixed solvent is 70:30.

[Example 10]

Regarding the organic EL device of Example 10, 2,3-dimethylnitrobenzene (bp: 245°C) used as the first aromatic solvent A in which solid components are dissolved is added as the second aromatic solvent B An ink containing a mixed solvent obtained from 3-phenoxytoluene (bp: 272°C) to form a hole injection layer 131, a hole transport layer 132, and a light emitting layer 133. The layer constituent material or film thickness of each layer is the same as in Comparative Example 1. The content ratio (A:B) of the above-mentioned mixed solvent is 90:10.

The above-mentioned Examples 6 to 10 are made to contain 2,3-dioxide as the first aromatic solvent A The content ratio (A:B) of the mixed solvent of methyl nitrobenzene (bp: 245°C) and 3-phenoxytoluene (bp: 272°C) as the second aromatic solvent B is different.

[Example 11]

Regarding the organic EL device of Example 11, 2,4-dimethylnitrobenzene (bp: 245°C) used as the first aromatic solvent A in which solid components are dissolved is added as the second aromatic solvent B An ink containing a mixed solvent obtained from 3-phenoxytoluene (bp: 272°C) to form a hole injection layer 131, a hole transport layer 132, and a light emitting layer 133. The layer constituent material or film thickness of each layer is the same as in Comparative Example 1. The content ratio (A:B) of the above-mentioned mixed solvent is 10:90.

[Example 12]

Regarding the organic EL device of Example 12, 2,4-dimethylnitrobenzene (bp: 245°C) used as the first aromatic solvent A in which solid components are dissolved is added as the second aromatic solvent B An ink containing a mixed solvent obtained from 3-phenoxytoluene (bp: 272°C) to form a hole injection layer 131, a hole transport layer 132, and a light emitting layer 133. The layer constituent material or film thickness of each layer is the same as in Comparative Example 1. The content ratio (A:B) of the above-mentioned mixed solvent is 30:70.

[Example 13]

Regarding the organic EL device of Example 13, 2,4-dimethylnitrobenzene (bp: 245°C), which is used as the first aromatic solvent A in which solid components are dissolved, is added as the second aromatic solvent B An ink containing a mixed solvent obtained from 3-phenoxytoluene (bp: 272°C) to form a hole injection layer 131, a hole transport layer 132, and a light emitting layer 133. The layer constituent material or film thickness of each layer is the same as in Comparative Example 1. The content ratio (A:B) of the above-mentioned mixed solvent is 50:50.

[Example 14]

Regarding the organic EL device of Example 14, it was used as the first aromatic solvent A, 2,4-dimethylnitrobenzene (bp: 245°C) in which solid components were dissolved, and added as the second aromatic An ink containing a mixed solvent obtained from 3-phenoxytoluene (bp: 272° C.) of the group solvent B forms a hole injection layer 131, a hole transport layer 132, and a light emitting layer 133. The layer constituent material or film thickness of each layer is the same as in Comparative Example 1. The content ratio (A:B) of the above-mentioned mixed solvent is 70:30.

[Example 15]

Regarding the organic EL device of Example 15, 2,4-dimethylnitrobenzene (bp: 245°C), which is used as the first aromatic solvent A in which solid components are dissolved, is added as the second aromatic solvent B An ink containing a mixed solvent obtained from 3-phenoxytoluene (bp: 272°C) to form a hole injection layer 131, a hole transport layer 132, and a light emitting layer 133. The layer constituent material or film thickness of each layer is the same as in Comparative Example 1. The content ratio (A:B) of the above-mentioned mixed solvent is 90:10.

The above-mentioned Examples 11 to 15 consist of 2,4-dimethylnitrobenzene (bp: 245°C) as the first aromatic solvent A and 3-phenoxytoluene as the second aromatic solvent B (bp: 272°C) the content ratio (A:B) of the mixed solvent is different.

Regarding the ink composition in the following comparative examples and examples, TDAPB is used as the host material, and Ppy2Ir is used as the luminescent material (guest material) for phosphorescence. The other composition is basically the same as the above-mentioned F8BT as the luminescent material for fluorescence.

[Comparative Example 4]

Regarding the organic EL element of Comparative Example 4, nitrobenzene (bp: 210°C) was used as the first aromatic solvent A, and VB-TCA as a hole injection material was dissolved in nitrobenzene to obtain an ink, and the obtained ink was used A hole injection layer 131 with a film thickness of 10 nm-30 nm is formed without the ink containing the second aromatic solvent B. In addition, an ink obtained by dissolving TFB as a hole transport material in nitrobenzene is used to form a hole transport layer 132 with a film thickness of 10 nm to 20 nm. Furthermore, using an ink obtained by dissolving the above-mentioned phosphorescent light-emitting material in nitrobenzene, a light-emitting layer 133 having a film thickness of 60 nm to 80 nm is formed. The structure of the other electron transport layer 134 and the electron injection layer 135 in the functional layer 136 is like the manufacturing method of the organic EL device 130 As explained in.

[Comparative Example 5]

Regarding the organic EL element of Comparative Example 5, it was used in nitrobenzene (bp: 210°C) as the first aromatic solvent A in which solid components were dissolved, and 2-methoxytoluene as the second aromatic solvent B was added (bp: 170° C.) The obtained ink containing the mixed solvent forms the hole injection layer 131, the hole transport layer 132, and the light emitting layer 133. The layer constituent material or film thickness of each layer is the same as that of Comparative Example 4. The content ratio (A:B) of the above-mentioned mixed solvent is 50:50.

[Comparative Example 6]

Regarding the organic EL device of Comparative Example 6, 1,3,5-as the second aromatic solvent B added to nitrobenzene (bp: 210°C) as the first aromatic solvent A in which solid components are dissolved An ink containing a mixed solvent obtained from triethylbenzene (bp: 215° C.) forms a hole injection layer 131, a hole transport layer 132, and a light emitting layer 133. The layer constituent material or film thickness of each layer is the same as that of Comparative Example 4. The content ratio (A:B) of the above-mentioned mixed solvent is 60:40.

[Example 16]

Regarding the organic EL element of Example 16, it was used to add 3-phenoxytoluene as the second aromatic solvent B to nitrobenzene (bp: 210°C) as the first aromatic solvent A in which solid components were dissolved. (bp: 272° C.) The obtained ink containing the mixed solvent forms the hole injection layer 131, the hole transport layer 132, and the light emitting layer 133. The layer constituent material or film thickness of each layer is the same as that of Comparative Example 4. The content ratio (A:B) of the above-mentioned mixed solvent is 10:90.

[Example 17]

Regarding the organic EL device of Example 17, it was used to add 3-phenoxytoluene as the second aromatic solvent B to nitrobenzene (bp: 210°C) as the first aromatic solvent A in which solid components were dissolved. (bp: 272° C.) The obtained ink containing the mixed solvent forms the hole injection layer 131, the hole transport layer 132, and the light emitting layer 133. The layer constituent material or film thickness of each layer is the same as that of Comparative Example 4. The content ratio (A:B) of the above-mentioned mixed solvent is 30:70.

[Example 18]

Regarding the organic EL element of Example 18, 3-phenoxytoluene as the second aromatic solvent B was added to nitrobenzene (bp: 210°C) as the first aromatic solvent A in which solid components were dissolved. (bp: 272° C.) The obtained ink containing the mixed solvent forms the hole injection layer 131, the hole transport layer 132, and the light emitting layer 133. The layer constituent material or film thickness of each layer is the same as that of Comparative Example 4. The content ratio (A:B) of the above-mentioned mixed solvent is 50:50.

[Example 19]

Regarding the organic EL device of Example 19, 3-phenoxytoluene as the second aromatic solvent B was added to nitrobenzene (bp: 210°C) as the first aromatic solvent A in which solid components were dissolved. (bp: 272° C.) The obtained ink containing the mixed solvent forms the hole injection layer 131, the hole transport layer 132, and the light emitting layer 133. The layer constituent material or film thickness of each layer is the same as that of Comparative Example 4. The content ratio (A:B) of the above-mentioned mixed solvent is 70:30.

[Example 20]

Regarding the organic EL element of Example 20, 3-phenoxytoluene as the second aromatic solvent B was added to nitrobenzene (bp: 210°C) as the first aromatic solvent A in which solid components were dissolved. (bp: 272° C.) The obtained ink containing the mixed solvent forms the hole injection layer 131, the hole transport layer 132, and the light emitting layer 133. The layer constituent material or film thickness of each layer is the same as that of Comparative Example 4. The content ratio (A:B) of the above-mentioned mixed solvent is 90:10.

[Example 21]

Regarding the organic EL device of Example 21, 2,3-dimethylnitrobenzene (bp: 245°C) used as the first aromatic solvent A in which solid components are dissolved is added as the second aromatic solvent B An ink containing a mixed solvent obtained from 3-phenoxytoluene (bp: 272°C) to form a hole injection layer 131, a hole transport layer 132, and a light emitting layer 133. The layer constituent material or film thickness of each layer is the same as that of Comparative Example 4. The content ratio (A:B) of the above-mentioned mixed solvent is 10:90.

[Example 22]

Regarding the organic EL device of Example 22, it was used as a solid component dissolved Containment mixture obtained by adding 3-phenoxytoluene (bp: 272°C) as the second aromatic solvent B to 2,3-dimethylnitrobenzene (bp: 245°C) in the first aromatic solvent A The solvent ink forms the hole injection layer 131, the hole transport layer 132, and the light emitting layer 133. The layer constituent material or film thickness of each layer is the same as that of Comparative Example 4. The content ratio (A:B) of the above-mentioned mixed solvent is 30:70.

[Example 23]

Regarding the organic EL device of Example 23, 2,3-dimethylnitrobenzene (bp: 245°C), which is used as the first aromatic solvent A in which solid components are dissolved, is added as the second aromatic solvent B An ink containing a mixed solvent obtained from 3-phenoxytoluene (bp: 272°C) to form a hole injection layer 131, a hole transport layer 132, and a light emitting layer 133. The layer constituent material or film thickness of each layer is the same as that of Comparative Example 4. The content ratio (A:B) of the above-mentioned mixed solvent is 50:50.

[Example 24]

Regarding the organic EL device of Example 24, 2,3-dimethylnitrobenzene (bp: 245°C), which is used as the first aromatic solvent A in which solid components are dissolved, is added as the second aromatic solvent B An ink containing a mixed solvent obtained from 3-phenoxytoluene (bp: 272°C) to form a hole injection layer 131, a hole transport layer 132, and a light emitting layer 133. The layer constituent material or film thickness of each layer is the same as that of Comparative Example 4. The content ratio (A:B) of the above-mentioned mixed solvent is 70:30.

[Example 25]

Regarding the organic EL device of Example 25, 2,3-dimethylnitrobenzene (bp: 245°C) used as the first aromatic solvent A in which solid components are dissolved is added as the second aromatic solvent B An ink containing a mixed solvent obtained from 3-phenoxytoluene (bp: 272°C) to form a hole injection layer 131, a hole transport layer 132, and a light emitting layer 133. The layer constituent material or film thickness of each layer is the same as that of Comparative Example 4. The content ratio (A:B) of the above-mentioned mixed solvent is 90:10.

[Example 26]

Regarding the organic EL device of Example 26, 2,4-dimethylnitrobenzene (bp: 245°C), which is used as the first aromatic solvent A in which solid components are dissolved, is added as the second aromatic solvent B An ink containing a mixed solvent obtained from 3-phenoxytoluene (bp: 272°C) to form a hole injection layer 131, a hole transport layer 132, and a light emitting layer 133. The layer constituent material or film thickness of each layer is the same as that of Comparative Example 4. The content ratio (A:B) of the above-mentioned mixed solvent is 10:90.

[Example 27]

Regarding the organic EL device of Example 27, 2,4-dimethylnitrobenzene (bp: 245°C), which is used as the first aromatic solvent A in which solid components are dissolved, is added as the second aromatic solvent B An ink containing a mixed solvent obtained by using 3-phenoxytoluene (bp: 272°C) to form a hole injection layer 131, a hole transport layer 132, and a light emitting layer 133. The layer constituent material or film thickness of each layer is the same as that of Comparative Example 4. The content ratio (A:B) of the above-mentioned mixed solvent is 30:70.

[Example 28]

Regarding the organic EL element of Example 28, 2,4-dimethylnitrobenzene (bp: 245°C), which is used as the first aromatic solvent A in which solid components are dissolved, is added as the second aromatic solvent B An ink containing a mixed solvent obtained from 3-phenoxytoluene (bp: 272°C) to form a hole injection layer 131, a hole transport layer 132, and a light emitting layer 133. The layer constituent material or film thickness of each layer is the same as that of Comparative Example 4. The content ratio (A:B) of the above-mentioned mixed solvent is 50:50.

[Example 29]

Regarding the organic EL element of Example 29, 2,4-dimethylnitrobenzene (bp: 245°C), which is used as the first aromatic solvent A in which solid components are dissolved, is added as the second aromatic solvent B An ink containing a mixed solvent obtained from 3-phenoxytoluene (bp: 272°C) to form a hole injection layer 131, a hole transport layer 132, and a light emitting layer 133. Layer composition of each layer The material or film thickness is the same as that of Comparative Example 4. The content ratio (A:B) of the above-mentioned mixed solvent is 70:30.

[Example 30]

Regarding the organic EL device of Example 30, 2,4-dimethylnitrobenzene (bp: 245°C) used as the first aromatic solvent A in which solid components are dissolved is added as the second aromatic solvent B An ink containing a mixed solvent obtained from 3-phenoxytoluene (bp: 272°C) to form a hole injection layer 131, a hole transport layer 132, and a light emitting layer 133. The layer constituent material or film thickness of each layer is the same as that of Comparative Example 4. The content ratio (A:B) of the above-mentioned mixed solvent is 90:10.

The method of evaluating the device characteristics of the organic EL device of this embodiment will be described. Regarding the driving voltage as the device characteristic, the driving voltage of Comparative Example 1 is set to "1", and the driving voltages of other Comparative Examples 2, 3, or Examples 1 to 15 are recorded as "◎ (good) when the driving voltage is less than 0.9 )", when it is 0.9 or more and less than 0.95, it is recorded as "○ (good)", when it is 0.95 or more and less than 1.05, it is recorded as "● (slightly poor)", and when it is 1.05 or more It is recorded as "× (bad)". Similarly, the driving voltage of Comparative Example 4 is set to "1", and the driving voltage of other Comparative Examples 5 and 6 or Examples 16 to 30 is marked as "◎ (good)" when the driving voltage is less than 0.9, and is If it is 0.9 or more and less than 0.95, it is recorded as "○ (good)", if it is 0.95 or more and less than 1.05, it is recorded as "● (slightly poor)", and if it is 1.05 or more, it is recorded as "× (bad)".

Regarding the current efficiency as the element characteristic, the current efficiency of Comparative Example 1 is set to "1", and the current efficiency of other Comparative Examples 2, 3 or Example 1 to Example 15 is recorded as "◎ (good) when the current efficiency is greater than 1.1 )", when it is 1.05 or more and less than 1.1, it is recorded as "○ (good)", when it is 0.95 or more and less than 1.05, it is recorded as "● (slightly bad)", when it is less than 0.95 It is recorded as "× (bad)". Similarly, the current efficiency of Comparative Example 4 is set to "1", and the current efficiency of other Comparative Examples 5 and 6 or Examples 16 to 30 is marked as "◎ (good)" when the current efficiency is greater than 1.1. When 1.05 or more and less than 1.1 is recorded as "○ (good)" is recorded as "● (slightly bad)" when it is above 0.95 and less than 1.05, and "× (bad)" when it is less than 0.95.

Regarding the life half-life time as a component characteristic, the life half-life time of Comparative Example 1 is set to "1", and the life half-life time of other Comparative Examples 2, 3 or Examples 1 to 15 is greater than 1.5 Recorded as "◎ (good)", "○ (good)" when it is 1.0 or more and less than 1.5, and "● (slightly bad)" when it is 0.9 or more and less than 1.0, In the case of less than 0.9, it is recorded as "× (bad)". Similarly, the life half-life time of Comparative Example 4 is set to "1", and the life half-life time of other Comparative Examples 5, 6 or Examples 16 to 30 is recorded as "◎ (good) when the life half-life time is greater than 1.5 ", when it is 1.0 or more and less than 1.5, it is recorded as "○ (good)", when it is 0.9 or more and less than 1.0, it is recorded as "● (slightly poor)", when it is less than 0.9 Recorded as "× (bad)".

Fig. 17 is a table showing the evaluation results of the device characteristics of the organic EL devices in Comparative Example 1 to Comparative Example 3 and Example 1 to Example 15, and Fig. 18 is a table showing Comparative Example 4 to Comparative Example 6 and Example 16 to implementation Table of the evaluation results of the device characteristics of the organic EL device in Example 30.

As shown in Figure 17, when using a luminescent material that obtains fluorescence, the device characteristics of the organic EL devices of Comparative Example 2 and Comparative Example 3, namely, driving voltage, current efficiency, and life half-life time, compared to Comparative Example 1, The evaluations are all "● (slightly bad)". On the other hand, in Examples 1 to 15, the evaluation of the device characteristics was "◎ (good)" or "○ (good)". Especially in the first aromatic solvent A and the second aromatic solvent B in the mixed solvent, the content ratio (A:B) is 10:90-50:50 Example 1~Example 3, Example 6~Example 8. In Examples 11 to 13, the driving voltage, current efficiency, and life half-life time are all "◎ (good)". In Example 4, Example 9, and Example 14 where the content ratio of the mixed solvent (A:B) is 70:30, the driving voltage and current efficiency are "◎ (good)", and the lifetime half-life time is "○( good)". Furthermore, in Example 5, Example 10, and Example 15 where the content ratio of the mixed solvent (A:B) was 90:10, the device characteristics were all "○ (good)".

As shown in Figure 18, in the case of using phosphorescent light-emitting materials, the same The same result is obtained when using fluorescent materials. Specifically, with respect to Comparative Example 4, the device characteristics of the organic EL devices of Comparative Example 5 and Comparative Example 6, that is, the evaluation of driving voltage, current efficiency, and lifetime half-life time are all "● (slightly poor)". In contrast, the content ratio (A:B) of the first aromatic solvent A and the second aromatic solvent B in the mixed solvent is 10:90-50:50 in Example 16~Example 18, and Example 21 ~ In Example 23, Example 26 to Example 28, the driving voltage, current efficiency, and life half-life time are all "◎ (good)". In Example 19, Example 24, and Example 29 where the content ratio of the mixed solvent (A:B) is 70:30, the driving voltage and current efficiency are "◎ (good)", and the lifetime half-life time is "○( good)". Furthermore, in Example 20, Example 25, and Example 30 in which the content ratio (A:B) of the mixed solvent was 90:10, the device characteristics were all "○ (good)".

According to the evaluation results of the device characteristics in the above-mentioned comparative example and the above-mentioned embodiment, if the content ratio (A:B) of the first aromatic solvent A and the second aromatic solvent B in the mixed solvent is 10:90~90:10 Within the range, the device characteristics of any solvent combination are improved in the comparative example. Furthermore, in an embodiment where the content ratio (A:B) of the mixed solvent is 10:90, 30:70, 50:50, that is, the content ratio of the second aromatic solvent B is equal to or higher than that of the first aromatic solvent A In the case of the content ratio, obtain more excellent device characteristics evaluation. Regarding the results of this evaluation, it is believed that the interaction (attractive force) between the first aromatic solvent A with electron-withdrawing properties and the second aromatic solvent B with electron-donating properties (attractive force), when the ink is dried and fired to form a film, is When the second aromatic solvent B with a higher boiling point evaporates, the first aromatic solvent A with a lower boiling point also evaporates. Thereby, the residue of the electron-attracting first aromatic solvent A in the film after film formation can be reduced. In other words, it is possible to suppress the effect of the electron-attracting first aromatic solvent A remaining in the film after film formation on the device characteristics, and provide a composition (ink) for forming a functional layer that obtains the required excellent device characteristics.

Furthermore, it is believed that the reason why the device characteristics of Comparative Example 2 are inferior to Comparative Example 1 is that the ink contains 2-methoxytoluene, which has a boiling point lower than nitrobenzene. Therefore, the drying speed of the ink becomes faster and the film flatness decreases. , Nitrobenzene remains in the film to affect the characteristics of the device. Compare The reason why the device characteristics of Example 5 are inferior to that of Comparative Example 4 is also the same.

The reason why the device characteristics of Comparative Example 3 are inferior to that of Comparative Example 1 is believed to be that although 1,3,5-triethylbenzene has a higher boiling point than nitrobenzene, its electron donating properties are lower than those used as the second aromatic in the examples. Solvent B is 3-phenoxytoluene, so the interaction between nitrobenzene and 1,3,5-triethylbenzene is weak, and nitrobenzene remains in the film after film formation, which reduces the device characteristics. The reason why the device characteristics of Comparative Example 6 are inferior to that of Comparative Example 4 is also the same.

In this embodiment, preferred examples of the first aromatic solvent A having an electron withdrawing group include nitrobenzene, 2,3-dimethylnitrobenzene, and 2,4-dimethylnitrobenzene. However, as the electron withdrawing group, in addition to the nitro group (-NO ₂ group), a cyano group (-NH ₃ group) may also be mentioned. It is believed that if the interaction between the organic EL material and the electron withdrawing group is taken into consideration, the influence of the interaction of the nitro group is less than that of the cyano group.

Moreover, as the electron withdrawing group, in addition to the nitro group, halogen groups (-F (fluoro group), -Cl (chloro group), -Br (bromo group), -I (iodo group)) can also be mentioned. However, it is known that halogen groups have stronger electron withdrawing properties than nitro groups. If a solvent with halogen groups remains in the functional layer, the device characteristics of the organic EL device will be significantly reduced due to the interaction between the organic EL material and the halogen groups. In other words, it is believed that the first aromatic solvent A having a nitro group as an electron-withdrawing group exhibits relatively low reactivity with organic EL materials.

On the other hand, as shown in the above examples, even if the ratio of the second aromatic solvent B in the mixed solvent content ratio (A:B) is increased, the device characteristics will not be affected, so it is considered to have an alkoxy group Or the second aromatic solvent B with an amine group as an electron-donating group shows almost no reactivity with the organic EL material.

That is, even if the solvent constituting the composition for forming a functional layer remains in the film after film formation, it is preferable to select the first aromatic solvent A and the second aromatic solvent B, which are less reactive with the organic EL material. . In addition, in the above-mentioned examples, one solvent was selected for each of the first aromatic solvent A and the second aromatic solvent B, but it is not limited to this, and a plurality of solvents may be selected separately. Furthermore, the mixed solvent is not limited to a mixture of the first aromatic solvent A and the second aromatic solvent. The composition of agent B, for example, in order to adjust the viscosity or surface tension of the ink, it may also include other aromatic solvents or surfactants with lower reactivity with organic EL materials.

It is disclosed above that the functional layer forming composition (ink) of the present embodiment is suitable for forming at least one of the functional layers by the inkjet method, but it can also be applied to other than the inkjet method, such as quantitative spraying or spin coating. Liquid-phase processes such as cloth method and spray method.

(Second Embodiment)

<Electronic Equipment>

Next, the electronic equipment of this embodiment will be described with reference to FIG. 19. FIG. 19(a) is a schematic diagram showing a notebook personal computer as an example of electronic equipment, and FIG. 19(b) is a schematic diagram showing a thin television (TV) as an example of electronic equipment.

As shown in Figure 19(a), a personal computer 1000 as an electronic device is composed of a main body 1001 with a keyboard 1002 and a display unit 1003 with a display unit 1004, and the display unit 1003 is rotatably rotated via a hinge structure. Supported by the main body 1001.

In the personal computer 1000, the organic EL device 100 of the first embodiment described above is mounted on the display unit 1004.

As shown in FIG. 19(b), a thin television (TV) 1100 as an electronic device is equipped with the organic EL device 100 of the first embodiment described above on the display portion 1101.

Regarding the organic EL element 130 provided in the sub-pixels 110R, 110G, and 110B of the organic EL device 100, at least one of the hole injection layer 131, the hole transport layer 132, and the light emitting layer 133 in the functional layer 136 uses the above-mentioned first The composition for forming a functional layer of the first embodiment is formed by a liquid phase process (inkjet method). Therefore, the film flatness of the functional layer 136 is ensured, and the organic EL device 100 having the organic EL element 130 with excellent element characteristics is manufactured. That is, it is possible to provide a personal computer 1000 or a thin TV1100 with excellent display quality and reliability quality.

The electronic device equipped with the organic EL device 100 is not limited to the personal computer 1000 or the thin TV 1100 described above. Examples include smartphones or POS (Point Of Sale), etc. Electronic devices with display units, such as portable information terminals, navigators, viewers, digital cameras, and direct-screen video recorders.

Furthermore, the organic EL device 100 is not limited to constituting a display portion, and may be an illumination device or an exposure device that exposes photosensitive objects.

The present invention is not limited to the above-mentioned embodiments, and can be appropriately modified within the scope that does not violate the gist or idea of the invention understood from the scope of the patent application and the full text of the specification, and the composition for forming a functional layer and the functional layer accompanied by such changes The manufacturing method of the forming composition, the manufacturing method of the organic EL element, the organic EL device, and the electronic equipment using the organic EL device are also included in the technical scope of the present invention. In addition to the above-mentioned embodiment, various modifications are also conceived. Hereinafter, a modified example will be described.

(Modification 1) The organic EL device 100 only needs to include the organic EL element 130 having the functional layer 136 formed using the functional layer forming composition of the present invention in any of the sub-pixels 110R, 110G, and 110B. For example, the sub-pixel 110R and the sub-pixel 110G can be provided with an organic EL element 130 having a functional layer 136 formed using a composition for forming a functional layer, and the sub-pixel 110B can be provided with a functional layer formed by a gas phase process. 136 organic EL element 130.

(Variation 2) The composition for forming a functional layer of the present invention is not limited to being used for forming the functional layer 136 including a light-emitting layer. For example, the solid component (organic material) as a solute may also be a circuit element forming material such as a semiconductor layer constituting an organic transistor.

Claims (12)

A composition for forming a functional layer, which is used when forming at least one layer of a functional layer containing an organic material, characterized in that it contains a solid component for forming a functional layer and a first aromatic solvent with an electron withdrawing group , And a second aromatic solvent having an electron donating group, the boiling point of the second aromatic solvent is higher than the boiling point of the first aromatic solvent, and the electron withdrawing group is a nitro group. The composition for forming a functional layer according to claim 1, wherein the boiling point of the first aromatic solvent is 200°C or higher, and the boiling point of the second aromatic solvent is 250°C or higher. The composition for forming a functional layer according to claim 1 or 2, wherein the electron donating group is an alkoxy group or an amino group. The composition for forming a functional layer according to claim 1 or 2, wherein the content of the second aromatic solvent is 10% or more and 90% or less. The composition for forming a functional layer according to claim 4, wherein the content ratio of the second aromatic solvent is equal to or higher than the content ratio of the first aromatic solvent. The composition for forming a functional layer according to claim 1 or 2, wherein the above-mentioned first aromatic solvent is selected from nitrobenzene, 2,3-dimethylnitrobenzene, and 2,4-dimethylnitrobenzene At least one of them. The composition for forming a functional layer according to claim 1 or 2, wherein the second aromatic solvent is selected from trimethoxy toluene, diphenyl ether, 3-phenoxy toluene, benzyl phenyl ether, and amino biphenyl , At least one of diphenylamine. A method for producing a composition for forming a functional layer, which is a method for producing a composition for forming a functional layer used when forming at least one of the functional layers containing an organic material The method is characterized by comprising the steps of dissolving the solid component for forming a functional layer in a first aromatic solvent having an electron withdrawing group, and dissolving the solid component for forming the functional layer in the first aromatic solvent In the step of adding a second aromatic solvent having an electron donating group, the boiling point of the second aromatic solvent is higher than the boiling point of the first aromatic solvent, and the electron withdrawing group is a nitro group. A method for manufacturing an organic EL device, which is a method for manufacturing an organic EL device in which a functional layer including a light-emitting layer is sandwiched between a pair of electrodes, is characterized in that it comprises: coating one of the above-mentioned pair of electrodes such as The step of the composition for forming a functional layer according to any one of claims 1 to 7, and the step of drying and curing the applied composition for forming a functional layer to form at least one of the functional layers. The method for manufacturing an organic EL device according to claim 9, wherein the step of coating the composition for forming a functional layer is to coat the composition for forming a functional layer on the film forming area on the one electrode by an inkjet method. An organic EL device characterized by having an organic EL element manufactured using the organic EL element manufacturing method of claim 9 or 10. An electronic device characterized by having an organic EL device as claimed in claim 11.

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